JK2 support in separate executable/library; option to compile renderers

Changed __NO_JK2 to JK2_MODE
Created new projects for openjo_sp(.x86.exe), jospgame(x86.dll) & rdjosp-vanilla_(x86.dll), which use JK2_MODE
Added BuildJK2SPRdVanilla etc. options for toggling creation of renderer projects independent of engine project creation.