New --bounds option to the diff operation to print out the boudning box of a diff instead of the diff itself.

There's also a new plumbing DiffBounds command for the java API.
So far the command assumes all features are in the same CRS.

co-author: Neelesh Bagga <nb287@cornell.edu>
Reset old/new envelope for each run in order to compare old/new object of the same entry only
Merge pull request #698 from groldan/diff_bounds

--bounds option to CLI's diff backed by a new DiffBounds plumbing command