Split core ImageJ commands into two components

[ctrueden]

From an imagej-devel mailing list thread:

Are you planing to re-organize the plugins, e.g. such that plugins,
which are interesting for any application reside in their own
jar-file?

The idea is to split the core IJ commands into two different components (i.e., JAR files): one intended for headless consumption, and one intended for the end user application (which will include e.g. the interactive meta-commands).

Migrated-From: http://trac.imagej.net/ticket/1953