Makes it so that the scripting cmake variable ENABLE_SCRIPTING is a user
variable rather than a global internal cmake variable, and defers the
internal global cmake variable to SCRIPTING_ENABLED instead.
Lua uses 1-based index on table insertions, and lua_newtable has a bit
better performance than lua_createtable if initializing tables with an
unknown item count.
Uses the 'install' command in cmake to install scripting modules/files
(such as _obspython.so, obslua.so, and obspython.py), and changes the
install location of those files on all operating systems. If using a
non-unix structure install, those files will be installed in
data/obs-scripting/[32bit/64bit], otherwise with unix structure installs
those files will be installed to [/usr/local/lib]/obs-scripting.
