Start of movement tests

Adds the following lua functions:

- nh.pushkey("x")
    Pushes a key into the command queue. Support is spotty,
    currently only the keys handled in rhack.
- nh.doturn()
    Runs one turn of main loop, or if optional boolean param
    is true, until g.multi == 0
- nh.monster_generation(false)
    Disable monster generation, and kill off all monsters.

Adds a testmove.lua script to test hero movement. Currently
covers only hjklyubn and HJKLYUBN.

include/extern.h

@@ -18,6 +18,7 @@ extern char *fmt_ptr(const void *);
 
 /* ### allmain.c ### */
 
+extern void moveloop_core(void);
 extern void moveloop(boolean);
 extern void stop_occupation(void);
 extern void display_gamewindows(void);