Allow use to choose a different SPI port and also ability to use my FlexSPI code

Added the ability to specify a different SPI port on the begin method.
like
```
ts.begin(SPI1);
```
And use SPI1 for the touch screen.

Also for T4.x as an experiment I added support to allow you to include my FlexIO library including the FlexSPI object :
My library is up at: https://github.com/KurtE/FlexIO_t4

I experimented with my version of Touchpaint_xpt2046;, with using different pins for the touch SPI pins than the display..
On T4.1 I tried using SPI1, with pins that would work for either SPI1 or FlexIO.

For FlexIO I could do:
```
FlexIOSPI SPIFLEX(Touch_MOSI, Touch_MISO, Touch_SCK, -1); // Setup on (int mosiPin, int sckPin, int misoPin, int csPin=-1) :
XPT2046_Touchscreen ts(Touch_CS);
```
And later I would do:
```
ts.begin(SPIFLEX);
```

Or since these are actually SPI1 bpins. could use the defines like before:
```
XPT2046_Touchscreen ts(Touch_CS);
```

And then in setup do:
```
  SPI1.setMISO(Touch_MISO);
  if (!ts.begin(SPI1)) {
```

Which appeared to work.

I tried adding the use of my flexIO library with the syntax like:
```
	#include <FlexIOSPI.h>
'''
So hopefully should not impact non T4 boards nor ones that don't have my libraries.

Author: KurtE

XPT2046_Touchscreen.cpp

@@ -30,9 +30,10 @@
 static XPT2046_Touchscreen 	*isrPinptr;
 void isrPin(void);
 
-bool XPT2046_Touchscreen::begin()
+bool XPT2046_Touchscreen::begin(SPIClass &wspi)
 {
-	SPI.begin();
+	_pspi = &wspi;
+	_pspi->begin();
 	pinMode(csPin, OUTPUT);
 	digitalWrite(csPin, HIGH);
 	if (255 != tirqPin) {
@@ -43,6 +44,25 @@ bool XPT2046_Touchscreen::begin()
 	return true;
 }
 
+#if defined(_FLEXIO_SPI_H_)
+#define FLEXSPI_SETTING     FlexIOSPISettings(2000000, MSBFIRST, SPI_MODE0)
+bool XPT2046_Touchscreen::begin(FlexIOSPI &wflexspi)
+{
+	_pspi = nullptr; // make sure we dont use this one... 
+	_pflexspi = &wflexspi;
+	_pflexspi->begin();
+	pinMode(csPin, OUTPUT);
+	digitalWrite(csPin, HIGH);
+	if (255 != tirqPin) {
+		pinMode( tirqPin, INPUT );
+		attachInterrupt(digitalPinToInterrupt(tirqPin), isrPin, FALLING);
+		isrPinptr = this;
+	}
+	return true;
+}
+#endif
+
+
 ISR_PREFIX
 void isrPin( void )
 {
@@ -100,30 +120,58 @@ static int16_t besttwoavg( int16_t x , int16_t y , int16_t z ) {
 void XPT2046_Touchscreen::update()
 {
 	int16_t data[6];
-
+	int z;
 	if (!isrWake) return;
 	uint32_t now = millis();
 	if (now - msraw < MSEC_THRESHOLD) return;
-	
-	SPI.beginTransaction(SPI_SETTING);
-	digitalWrite(csPin, LOW);
-	SPI.transfer(0xB1 /* Z1 */);
-	int16_t z1 = SPI.transfer16(0xC1 /* Z2 */) >> 3;
-	int z = z1 + 4095;
-	int16_t z2 = SPI.transfer16(0x91 /* X */) >> 3;
-	z -= z2;
-	if (z >= Z_THRESHOLD) {
-		SPI.transfer16(0x91 /* X */);  // dummy X measure, 1st is always noisy
-		data[0] = SPI.transfer16(0xD1 /* Y */) >> 3;
-		data[1] = SPI.transfer16(0x91 /* X */) >> 3; // make 3 x-y measurements
-		data[2] = SPI.transfer16(0xD1 /* Y */) >> 3;
-		data[3] = SPI.transfer16(0x91 /* X */) >> 3;
+	if (_pspi) {
+		_pspi->beginTransaction(SPI_SETTING);
+		digitalWrite(csPin, LOW);
+		_pspi->transfer(0xB1 /* Z1 */);
+		int16_t z1 = _pspi->transfer16(0xC1 /* Z2 */) >> 3;
+		z = z1 + 4095;
+		int16_t z2 = _pspi->transfer16(0x91 /* X */) >> 3;
+		z -= z2;
+		if (z >= Z_THRESHOLD) {
+			_pspi->transfer16(0x91 /* X */);  // dummy X measure, 1st is always noisy
+			data[0] = _pspi->transfer16(0xD1 /* Y */) >> 3;
+			data[1] = _pspi->transfer16(0x91 /* X */) >> 3; // make 3 x-y measurements
+			data[2] = _pspi->transfer16(0xD1 /* Y */) >> 3;
+			data[3] = _pspi->transfer16(0x91 /* X */) >> 3;
+		}
+		else data[0] = data[1] = data[2] = data[3] = 0;	// Compiler warns these values may be used unset on early exit.
+		data[4] = _pspi->transfer16(0xD0 /* Y */) >> 3;	// Last Y touch power down
+		data[5] = _pspi->transfer16(0) >> 3;
+		digitalWrite(csPin, HIGH);
+		_pspi->endTransaction();
+	}	
+#if defined(_FLEXIO_SPI_H_)
+	else if (_pflexspi) {
+		_pflexspi->beginTransaction(FLEXSPI_SETTING);
+		digitalWrite(csPin, LOW);
+		_pflexspi->transfer(0xB1 /* Z1 */);
+		int16_t z1 = _pflexspi->transfer16(0xC1 /* Z2 */) >> 3;
+		z = z1 + 4095;
+		int16_t z2 = _pflexspi->transfer16(0x91 /* X */) >> 3;
+		z -= z2;
+		if (z >= Z_THRESHOLD) {
+			_pflexspi->transfer16(0x91 /* X */);  // dummy X measure, 1st is always noisy
+			data[0] = _pflexspi->transfer16(0xD1 /* Y */) >> 3;
+			data[1] = _pflexspi->transfer16(0x91 /* X */) >> 3; // make 3 x-y measurements
+			data[2] = _pflexspi->transfer16(0xD1 /* Y */) >> 3;
+			data[3] = _pflexspi->transfer16(0x91 /* X */) >> 3;
+		}
+		else data[0] = data[1] = data[2] = data[3] = 0;	// Compiler warns these values may be used unset on early exit.
+		data[4] = _pflexspi->transfer16(0xD0 /* Y */) >> 3;	// Last Y touch power down
+		data[5] = _pflexspi->transfer16(0) >> 3;
+		digitalWrite(csPin, HIGH);
+		_pflexspi->endTransaction();
+
 	}
-	else data[0] = data[1] = data[2] = data[3] = 0;	// Compiler warns these values may be used unset on early exit.
-	data[4] = SPI.transfer16(0xD0 /* Y */) >> 3;	// Last Y touch power down
-	data[5] = SPI.transfer16(0) >> 3;
-	digitalWrite(csPin, HIGH);
-	SPI.endTransaction();
+#endif
+	// If we do not have either _pspi or _pflexspi than bail. 
+	else return;
+
 	//Serial.printf("z=%d  ::  z1=%d,  z2=%d  ", z, z1, z2);
 	if (z < 0) z = 0;
 	if (z < Z_THRESHOLD) { //	if ( !touched ) {

XPT2046_Touchscreen.h

@@ -26,6 +26,12 @@
 #include "Arduino.h"
 #include <SPI.h>
 
+#if defined(__IMXRT1062__)
+#if __has_include(<FlexIOSPI.h>)
+	#include <FlexIOSPI.h>
+#endif
+#endif
+
 #if ARDUINO < 10600
 #error "Arduino 1.6.0 or later (SPI library) is required"
 #endif
@@ -43,7 +49,11 @@ class XPT2046_Touchscreen {
 public:
 	constexpr XPT2046_Touchscreen(uint8_t cspin, uint8_t tirq=255)
 		: csPin(cspin), tirqPin(tirq) { }
-	bool begin();
+	bool begin(SPIClass &wspi = SPI);
+#if defined(_FLEXIO_SPI_H_)
+	bool begin(FlexIOSPI &wflexspi);
+#endif
+
 	TS_Point getPoint();
 	bool tirqTouched();
 	bool touched();
@@ -59,6 +69,10 @@ class XPT2046_Touchscreen {
 	uint8_t csPin, tirqPin, rotation=1;
 	int16_t xraw=0, yraw=0, zraw=0;
 	uint32_t msraw=0x80000000;
+	SPIClass *_pspi = nullptr;
+#if defined(_FLEXIO_SPI_H_)
+	FlexIOSPI *_pflexspi = nullptr;
+#endif
 };
 
 #ifndef ISR_PREFIX