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? YES! Unless running from a floppy?

^S and ^Q to pause/resume displays.

ECHO, COPY, BREAK commands on command-line.

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

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

Add wildcard support to REN.

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

Support '>>' redirection.  Currently this overwrites files instead of
adding to them.

Add INT23 Handler.

Find out why command crashes when trying to exit.