Fix "trema --version" bug (fixes #248).
Upgrade gli (refs #248)
Add cucumber scenarios for trema --help option (refs #247).
Simplify test case.
Merge pull request #249 from y-higuchi/fix_iterate_list_on_empty_list

Fix iterate_list to be usable on empty list.
Merge branch 'develop' into switchd_branching
Change command name.
Add header to trema.h
Add test case for low level API.
Do not assert on invalid external input.
Add test cases for reply.
Sort test case order.