4.0.0 Preview 2

Changes since 4.0.0 Preview 1

• Made some changes to IHashMap
• Made some changes to HashMap
• Added missing xml doc comments for:
  • Assembly extensions
  • bool extensions
  • char extensions
  • Dictionary extensions
  • string array extensions
  • Version extensions
• Changed some instances of String concatenation to string interpolation for improved performance
• Merged two Version extension method consutructors into one with an optional parameter
• Made internally used strings internal only