Improved release tarball script, via the main CLI.

Uses 'git describe' to generate the release version string.
Merge pull request #211 from hjoliver/improved-release-script

Improved release tarball script, via the main CLI.
cylc gui: reduce poll of a stopped suite.

Gradual increase of poll delay of a stopped suite.
Note: Because each view is updated by its own thread, destroying a view
will reset the poll delay.
Merge pull request #213 from matthewrmshin/197.cylc-gui-poll

cylc gui: reduce poll of a stopped suite.
Rewrite doc/{process,cleanup.sh} as a Makefile.
doc/Makefile: fix multi/single HTML clash.
Merge pull request #216 from matthewrmshin/doc-make

doc/Makefile to replace doc/process?