#1127: sed-based upgrade helper prototype
add a test
fix symlink
update following feedback
add monthly/yearly/etc disclaimer
add daily, monthly, yearly warnings
add new test, fix ict -> icp
Merge branch 'master' of github.com:cylc/cylc into cylc.upgrade-warning-maker
Merge pull request #1131 from benfitzpatrick/cylc.upgrade-warning-maker

cylc 5 to cylc 6 conversion helper tool