Don't try any console drawing if drawers are disabled
Escape scripting error messages so they are valid markup

Move generic keybindings (shift/alt/ctrl/meta/super) into new
D_Responder handler

Only take a screenshot if the menu and console have passed on the event;
this actually fixes the screenshot bug mentioned in the source

Reformat M_Responder

Convert HU_Responder and M_Responder to use the keybindings global
instead of static shiftdown (etc.) variables
Move global actions (screenshot, gamma, etc.) into D_Responder

Add doom_echo method to avoid warnings using doom_printf and static strings
Don't eat modifier key events (ctrl/shift/etc.)
Fix layout width miscalculations due to bad parens
Some small cosmetic console tweaks
Shift the console's input line properly depending upon cursor position

Fix exit when changing resolution
Console will now scroll through the scrollback
doom_printf and doom_echo now write to the console as well