Silence some Windows compiler warnings

by adding explicit type casts.
Convert all includes to relative paths.
Fix Linux build
Dolphin now builds on Linux with only Source/Core as include dir
Merge pull request #79 from Tilka/nits

Silence some Windows compiler warnings
Save frame skipping option, and allow loading it from game ini too.
Scope the Windows include directory to only point to Source/Core/.

Also fix the Windows build with this change.
Fix the OSX build.

Turns out Dolphin uses some macros that clash on OSX. However thankfully, this include is only used in Frame.cpp.
Merge pull request #87 from RachelBryk/save-frame-skip

Save frame skipping option, and allow loading it from game ini too.
Add an automated tool that does basic checking of includes sort order.
Fix more header sorting issues in Common/ (now check-includes clean).
Fix more header sorting issues in DiscIO/ (now check-includes clean).
Fix more header sorting issues in AudioCommon/ (now check-includes clean).
Fix more header sorting issues in InputCommon/ (now check-includes clean).
Fix more header sorting issues in VideoCommon/ (now check-includes clean).
Fix more header sorting issues in DolphinWX/ (now check-includes clean).
Fix more header sorting issues in VideoBackends/ (now check-includes clean).
Fix LinearDiskCache.h relying on a file not directly included.
Fix more header sorting issues in Core/ (now check-includes clean).
Fix the Windows build in relation to the recent changes.