Revert "Use capitalized exe name on Windows."

This reverts commit 4ea5fa532ce66d9ef19aa9691e597242eacdbfc2.
Better implementation of "Capitalize exe name on Windows".
Whitespace.
Make Performous-cmd.exe compile also on MinGW.
Re-arrange some CMake lines.
Debug -> RelWithDebInfo.
A potentially dangerous hack to allow GCC 4.6 still to be used (until users upgrade to 4.7 that supports the override keyword). Closes #42.
Note to self: test before commit. This should fix issue #42 for real (not tested on 4.6, still).
Audio bug fixing and cleanup. Should fix the problem reported in bug #38 (PulseAudio not working).
Get rid of super expensive glFinish calls in mainloop.

Keep them when profiling, now tied to benchmarking mode option.
Display cover image in jukebox mode (the layout could be better but this is a good starting point).
Implement better fallback for songs with no background image or video.

- Tiled screen appears only when the playing song is changed
- Heuristics for determining if the background/cover should be tiled or fullscreen
- Background is not drawn behind a video
- Tiling drawn as one Surface::draw call
- Animation to keep things more lively
- Added pixel width/height accessors to Surface
Fix automatic guessing of cover/bg/video files.

- Avoid TXT header reparsing overwriting the values guessed earlier
- Fix regex mistakes that caused most matches to fail
Rewrite filename guessing logic with less copypasta and with proper logging.
Songparser-TXT cleanup. Needs testing with files that have this extra line.
Change filenames to use fs::path and absolute paths instead of relative to song folder. Remove useless copypasta from song parsers. Incomplete work, has bugs.
Avoid re-processing of header fields in songparser-sm too, alike the earlier change in songparser-txt.
Put song browser menu at the bottom on all aspect ratios.

This is hacky as it's hardcoded instead of coming from a themefile.
However, the current theme position deduction can't handle
different aspect ratios or anchor points (AFAIK).
Clear screen each frame to prevent graphics glitches.
Instrument icons: reposition, enlarge and add glow.