MediaFormats: RAR was incorrectly flagged as audio-only.

Fixes #3088
update Changelog.txt, thirdparty/versions.txt and release date.
Update Greek translation.

refs PR 76
MP4Splitter: fixed playback for same 3gp with AMR sound (fixed 4496) (ticket #3079)
Audio Switcher: Improve normalization algorithm.

Use a much better regain strategy (similar to ffdshow's) and fix the regain rate to be linear rather than completely exponential.

This commit fixes #1936.
Audio switcher: Use percentage instead of dB for the boost.

Internally a percentage was already used and it is much easier for the user to understand a boost expressed in percentage.
Audio Switcher: Add a setting to change the max normalization factor.

Use a max normalization factor of 4 by default instead of 10 to avoid huge volume variations.

Refs: #1936.
Bump version to 1.6.8.
run astyle
update lcms to 5bf9e43
Updated Simplified Chinese translation.
Partially re-write CVMROSD, this fixes a case of truncated pointers on x64, adds minor performance improvements and adds extensive ASSERT and TRACE functionality for debug builds.
Change the functions for detecting the display adapter in MPCVideoDecFilter for DXVA uses. Note that when not directly connected to the DXVA2 interface functions (EVR mostly), this function queries the adapter the main video window is on. That adapter is not necessarily the adapter the video renderer will be using, so this system is not ideal at all.
Change a few types, optimize a few loops for CDXAReader. Change _tcstol() to _tcstoul() once, as _tcstol() is only meant for signed integers.
Optimize and simplify the two ExtractMediaTypes functions in DSUtil.
Optimize HMSF2RT() in DSUtil.
Optimize the ConvertMBCS() and UrlEncode() functions.
Edit Scale2x.cpp: make the SSE2 routines x86 compatible, re-order EMMS instructions for MMX routines (SSE-level builds only), change the SSE2 and MMX routines to reside inside the same functions, implement compiler context switches, comment out unused functions, mark functions as static __forceinline and extern appropriately. No changes in functionality of the Scale2x() function.
Manually inline functions that were already marked for integration (__forceinline). Add CPUID -dependent context switches to the existing compiler context switches. No changes in functionality. Similar issues like the ones are/were present in Scale2x.cpp are also present in AvgLines.cpp, it could use the same optimizations.
libmpeg2; Remove a warning disable, remove inline assembly, edit the c++ code in copy_chunk() to avoid pointer aliasing performance issues, decrease the main loop size and correct some wrong types for working objects.