Ict passed through to prereq types and handled.
Merge remote branch 'upstream/master' into pre-initial-ignore

Conflicts:
	lib/cylc/config.py
Conditional simplifier added and working.
Corrected splitting of strings bug.
Cleaned print statements.
Tidied up unnecessary labels and messages.
Whitespace correction.
Merge remote branch 'upstream/master' into pre-initial-ignore
Comment and remove redundant calls to simplify.py
Merge remote branch 'upstream/master' into pre-initial-ignore
Merge remote branch 'upstream/master' into pre-initial-ignore
Merge pull request #576 from arjclark/pre-initial-ignore

cylc prerequesites: ignore pre-initial cycle tasks