Support starting maps in directories via command line

[tdauth]

The Reforge World Editor supports saving maps in directories. To test development versions of maps it would help to have a command line option -loaddir similar to -loadfile which loads map directories and starts the map or -loadfile could also simply support directories.

For directories I get:

Exception in thread "LWJGL Application" java.lang.IllegalArgumentException: No such map file: ../wowr.w3x