Command line export

This PR adds command-line export for pre-constructed .flump project files. It is frequently true that the only reason to pop open flump is to load a .flump project file and press "export all" or (the new) "export combined". This system just does that from the command line. 

Executing the installed flump binary with --export <.flump path> will do just that, with sending the output to <app resource dir>/exporter.out (since Flex/AIR apps do not have access to the process stdout stream). The rsrc/flump-export script streamlines that process a bit on Macs, automatically executing against the default install location (customizable via $FLUMP_HOME), and tailing the output log file so it acts more like a standard command line script. Someone with the batch file know-how and desire should be able to spin up a similar tool for Windows without too much trouble.

As with the PR for combined export, we'll make use of this for awhile on Antihero and leave the PR open to community comment for some time before merging it in.