AppVeyor: add cygwin and minGW support

AppVeyor: add cygwin and minGW support

- Changes in platform configuration, x86 breaks the build
- Solution file does not contain platform for Any CPU, fixing it to Win32
- Added Multiple solutions to appveyor configuration file
- Added batch script for VS2010 builds
- Added fixes to appveyor.bat file and appveyor.yml
- Fixes for Platform and Configuration in appveyor.bat
- Fixed windows exit code, Appveyor reports exit on succesful build
- Multiple Builds in same platform and configuration, fixed it
- Added appveyor configuration to compile using MinGW 32-bit and 64-bits
- Minor Fixes for batch file and Added cygwin build script

Signed-off-by: Ludovic Rousseau <ludovic.rousseau@free.fr>