* it is now possible to switch back to the main intro loop from the fullscreen console.
* do not distort the background of the fullscreen console. Always draw the console on top of what the main loop currently displays with a translucent black overlay.
* do not use the CONPIC for the fullscreen console as it tends to be more of a distraction than an asset when filling the entire screen.
* cleaned up c_console.cpp and moved several pieces of code unrelated to actual console management out of it.
- added Marisa Kirisame's CHAN_OVERLAP flag.
- exported S_IsActorPlayingSomething to ZScript.
The sound API change required deprecating A_PlaySound and S_Sound. There are now new variants S_StartSound and A_StartSound which have two distinct parameters for channel and flags.
