Various improvements to dexdeps.

This includes:
* Adding an option to only produce lists of dependent classes (and not
  also fields and methods).
* Adding the ability to process multiple files on a single invocation.
* Adding a label at the head of the section for each file.
* Neatening up Output a bit by factoring "System.out" into a static field.

Change-Id: Id9a691d23afd18f82ab3790cb760cfd12e14bc86
3 files changed