implement Mutually Exclusive Groups
passes lint, test/testgroup.js and runs test/group.coffee
group.coffee tests group and exclusive groups a bit more than testgroup.js
but isn't structured as a test.
minor cleanup
generalize testgroup error matching
lint fix
Correct handling of groups that are passed from a parent parser to child.

As in ArgumentParser, use actionHash(action) as a groupMap key
in ActionContainer._addContainerActions
Correct Action.getName() so it tests .dest against null, not undefined
(its default value is null)
test/childgroups.js tests this case. Setup case is a bit contrived.
remove nonstandard example and test files
Merge pull request #32 from hpaulj/actionconst

Improved options check for storeConst & appendConst, closes #31
Merge pull request #30 from hpaulj/exclusive

Exclusive
history update
Fixed lint warnings
forsed error on unused vars in jshint
0.1.10 released
Merge branch 'test_argparse_py' into runs_py_tests