* imgcodecs cmake: the option to customize supported formats list (WITH_IMGCODEC_HDR, WITH_IMGCODEC_SUNRASTER, WITH_IMGCODEC_PXM)

* imgcodecs: fixes

- fixed CMake scripts (=OFF doesn't really work)
- restore dropped GDCM block
- added _IMGCODEC_ prefix
- fixed tests
- include PAM format under WITH_IMGCODEC_PXM option

- renamed source files
- guard the contents - always include

 - Resolved GET_ENV and input type incompatibility
 - Made libjpeg compile for WINRT. So does imgcodecs module.
 - Updated .gitignore (log, tlog)

- Substituted HAVE_WINRT with WINRT
- Fixed compilation issues in ocl.cpp and parallel.cpp
- Fixed compiler issue for WP8: "C2678: binary '+' : no operator found which takes a left-hand - Fixed gitignore
- Added #ifdef HAVE_OPENCL to remove compiler warnings in ocl.cpp
- Used NO_GETENV similar to '3rdparty\libjpeg\jmemmgr.c;
- Added ole32.lib for core module (for WindowsStore 8.0 builds)
- Made OpenCV_ARCH aware of ARM
Signed-off-by: NMaxim Kostin <v-maxkos@microsoft.com>