Work on Shapely dependency.

Start hxlfilter tests.
Test at the script-invocation level now.
More-sophisticated filter tests.
Change hxlfilter to use logical OR for multiple filters in the same
command (use multiple instances in a pipeline for logical AND).
Changed back to distutils.
Switch to a run() function.
Remove unneeded imports.
Moved run function back to hxl.commands.hxlfilter to simplify unit
testing; will do the same for the other scripts, gradually.
Start testing hxlfilter for lessthan (currently fails).
< operator working for hxlfilter
Add support for > operator in hxlfilter.

Rename hxlfilter test files to be more mneumonic
Complete operators for hxlfilter: =, !=, <, <=, >, >=
Update docstrings.
Merge branch 'master' into dev
Moved hxlcount execution code to hxl.commands.hxlcount
Clean up test file names.

Add first unit test for hxlcount