Cosmetics: build.bat and gccbuild.bat error handling improvements.
Add /Nocolors switch to disable colors in batch files output.
Use /Silent and /Nocolors switch for gccbuild when building through MSVC.
Avoids unneeded pause message.
Don't try to color output in MSVC.
Merge pull request #49 from kasper93/batch

Batch files improvements
Update CpuId to detect SSE4/4.2 and AVX support.
Disable completely the file assocs page when the user's rights are too low.

The edit box for extensions wasn't disabled as it should have been.