Update of CSharp sample

Dear abv,
Please, review the branch CR24147

I have made a few corrections and pushed to the same branch CR24147 (see message in last commit for details). Please review.

I reviewed branch CR24147. In my opinion all is Ok.

Sergey, please use branch CR24147 as starting base for WPF sample. I suggest you start from reproducing the same functionality as implemented in IE executable with Windows Forms, using WPF. Switch the issue to resolved when it is ready.

Dear abv,
Please, review the branch CR24147

Reviewed, please test; use branch CR24147_1.

Please consider adding CSharp sample (two executables: WinForms and WPF) to Start menu in Windows installer.

1. Export to images works incorrect in WinForms samples. There is an exception "Cann't write this file" (but file was successfully written). And all this message is incorrect (should be can't or can not).
2. Option "Export image to .xwd" should be removed 'cause there is no opportunity to save file in .xwd (trying to do this we get file a.xwd.bmp).
3. It's impossible to export file in any format in WPF sample. There is import instead of export.

Operation "Export" in the WPF sample has been fixed.

Please, review the branch CR24147_1

Reviewed, please test and integrate. My only remark is that perhaps formats other than BMP copuld be enabled in saving images (at least, PNG), however this is not really important.

Tested