saved in the user's configuration (last.dir) and restored
when DrJava is started. If the previous directory doesn't
exist anymore, DrJava will move towards the root of the
file system until an existing directory is found. If that
fails too, then the value of "user.home" is used.
M src/edu/rice/cs/drjava/model/AbstractGlobalModel.java
M src/edu/rice/cs/drjava/ui/MainFrame.java