Multi-task selection for control commands.
Operate on families (trigger, reset, etc.) in gcylc.
Factored out some common gui code.
Exclude intermediate families from matched tasks.
Allow prep commands to take a file path instead of suite name.

Closes #419.
Same for get-config command.
Handle commands with no suite arg (e.g. scan).
Better variable name.
Fix search command for file path arg.
Take cylc-suite-env write out of task jobfiles.
Finished deprecating CYLC_SUITE_REG_NAME
Create suite env parent dir if necessary.
Get proper PID for local and remote background jobs.
Merge pull request #425 from hjoliver/reimplement-cylc-suite-env

Reimplement cylc suite env file write
Merge pull request #424 from hjoliver/419.prep-by-file-path

419.prep by file path
Merge branch 'master' into 74.multi-task-control

Conflicts:
	lib/cylc/CylcOptionParsers.py
Merge pull request #416 from hjoliver/74.multi-task-control

74.multi task control