Added functionality to add commands within the repl. In addition to this...

I added a way to create built in commands for elm-repl. If the line starts with a colon it signals that a command will follow. I also added the following commands:

src-dir=path

Adds a path to be used for external libraries within the repl

src-dir

Displays the current list of paths being searched

remove-src-dir=path

Removes a path if it exists.

clear-src-dir

Removes all paths.