Reorder Variables.cmake for mergeability
Renames CMake Variables:
FMODSTUDIO->USE_FMODSTUDIO, NVAPI->USE_NVAPI,
VIEWER_CHANNEL_BASE->VIEWER_CHANNEL_TYPE
VIEWER_BRANDING_ID->VIEWER_BINARY_NAME,
VIEWER_PRODUCT_NAME->VIEWER_CHANNEL_BASE
Remove unused variables:
VIEWER_PACKAGE_ID, VIEWER_EXE_STRING, VIEWER_SHORTCUT_STRING, VERSION_BUILD
PACKAGE now defaults to on, USE_FMODSTUDIO now defaults to off
Use list append instead of set in some more places
Adds support for Project channels.
