* Update .travis.yml and use stages
This updates the .travis.yml configuration to use separate stages for
unittests and CLI tests. The output is now clearer, since for unittests
and CLI tests separate web pages are available.
* Use go modules and simplify build
- Fix display of CJK wide characters
- Fix horizontal offset of header lines
- Add support for keys with ALT modifier, shift-tab, page-up and down
- Fix util.ExecCommand to properly parse command-line arguments
- Fix redraw on resize
- Implement Pause/Resume for execute action
- Remove runtime check of GOOS
- Change exit status to 2 when tcell failed to start
- TBD: Travis CI build for tcell renderer
- Pending. tcell cannot reliably ingest keys from tmux send-keys
