0024147: Update of CSharp sample

0024147: Update of CSharp sample

Overall revision of of CSharp sample code:
- Pure C++ project "OCC" deleted as unnecessary
- C++/CLI project "shell" renamed to OCCTProxy and refactored to implement all required interface to OCCT functionality.
- In About dialog, date corrected in Copyright statement
- CSharp files re-layouted with 2 spaces indentation
- ReadMe converted to MarkDown format and revised
- Generation of names of views refactored to avoid calling C++ level
- Project files corrected to run on 64-bit systems
- Batch scripts refactored to use OCCT default configuration

WPF front-end added to demonstrate usage of OCCT in WPF applications.
WPF sample was modified, operation Export has been fixed
Exception "Cannot create this file", which appeared by export to image format, has been corrected.
Option "Export image to .xwd" removed.