add some more comments to am_map.c and remove unused code
Lost Souls spawned by Pain Elementals now also bleed Puffs

those dirty little bastards!

fixes #33
fix flats get more distorted the closer they are to the right
some improvements to st_stuff.c

- do not include m_menu.h anymore, instead declare "extern int
  screenblocks"
- add more comments, extensively
- restructure cheat codes
  - as part of the "Back to the Roots" campagn, remove all "if
    (singleplayer)" checks: cheats are disabled in netgames and screw
    up demo recording anyway.
  - unconditionally give backpacks in ID[K]FA
  - unconditionally eat keypress in IDCLEVx
  - sort cheats into the original ones, take opportunity to re-indent
- make "byte* ST_WidgetColor()" static
- do not unconditionally set "dp_translation = NULL" anymore
improvements to d_main.c

- add and improve comments
- re-order variables, initialize booleans
- rename "map" variable to "menushade"
- remove "singleplayer" conditional from SSG resources check: adding them
  manually to Doom 1 is explicit enough and should not require another
  sanity check