Add new features and fix some bug.

Added the following EXPERIMENTAL features(called Prototype):
  - Add-AbstractMethod
  - Add-AbstractProperty
  - Add-Field
  - Add-Method
  - Add-OverrideMethod
  - Add-OverrideProperty
  - Add-Property
  - New-Prototype
  - Set-New

  About the usage, please see some integrated test cases that are defined in Prototype.psm1.Tests.ps1.

In the feature PSUnitEx that improves the PSUnit usability, changed the interfaces. Because I understood wrongly about how to evaluate function parameters in PowerShell.