Things to do
~~~~~~~~~~~~
Fix bugs :)

Support the DOS=HIGH directive in CONFIG.SYS

Optimize the code!  For size and speed.  There are numerous places where the
code is hardly optimal for either.

Swap out when exec'ing?

^S and ^Q to pause/resume displays.

ECHO, TYPE, COPY, BREAK commands on command-line.

Implement /S flag for DIR.

Fix environment handling, probably using Steffan Kaiser's library.

Run autoexec.bat on startup.

Find and fix NULL pointer assignment (shows up when compiling in small model).

Add wildcard support to DEL, REN.

Allow customization at compile time to take out history, aliasing, etc.
