[CR] Deathcam Implementation

This should be a testworthy implementation (finally!) of viewing stuff happen after death. The code had to be inserted in various points, so be sure to point out any better ways to do what I have done. It is mostly rough draft at this point, but if there are no major issues, merge away gents. Enjoy!

Please do email me with any issues or question, or hit me up on IRC if I am there (DavekDOS usually).

I hope this is what you guys were looking for!
Probably needs to have `("DEFAULTMODE")` here, too. Otherwise the input context is created with the category "default" (see input.h) and won't match the context used in `game::get_player_input`.