Change special keys into extended commands

Changes most of the special keys used in the main input loop
into extended commands:

- movement keys are now bound to extended commands, eg.
  #movewest and so on.

- m-prefix is now #reqmenu extended command, still bound to
  the 'm' key.

- run, rush, and fight are now extended commands, still bound
  to the same keys as previously.

- nopickup and runnopickup keys are removed.
  Nopickup was using 'm' key, the same as the m-prefix, so
  allow #reqmenu to modify movement commands to disable pickup.

- multiple prefix commands are allowed. This lets user to
  use #reqmenu, followed by #run, followed by movement to simulate
  runnopickup behaviour. (If necessary, adding runnopickup back
  as an extended command would be easy)

doc/fixes37.0

@@ -747,6 +747,7 @@ when two or more shops share a wall and hero uses Passes_walls to carry an
 	unpaid item from the first shop wasn't noticed
 redo the unpaid_cost fix to handle shop items inside hero-owned container
 flyers shouldn't fall on arrival when going down holes or trap doors
+change movement keys and some special keys into extended commands
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository