VideoConfigDiag: Use uniform capitalization.

Nouns should be written capitalized for consistency.
DolphinWX: Remove yet another clamp method
DolphinWX: Remove unnecessary true within event Skip calls
Merge pull request #599 from lioncash/skips

DolphinWX: Remove unnecessary true within event Skip calls
Merge pull request #594 from lioncash/another-clamp-removal

DolphinWX: Remove yet another clamp method
Change SPADStatus struct name to GCPadStatus

Also get rid of the typedef, since this is unnecessary in C++
Merge pull request #601 from lioncash/pad-struct

Change SPADStatus struct name to GCPadStatus
Merge pull request #593 from neobrain/master

Use uniform capitalization in VideoConfigDiag
CMake: warn on missing declarations
mark all local functions as static
CMake: warn on missing variable declarations
mark all local variables as static
avoid the extern keyword in .cpp files
remove unused globals

Also change globals into statics which are only used in one file
Merge pull request #579 from degasus/statics

Mark unexported global variables and functions as statics.
InputCommon: Use enums instead of defines within GCPadStatus.h