Some tweaks and fixes for integer cycling.
add cylc migration info
Proper section anchors, but not TOC
add advanced R1 information
Merge pull request #1125 from benfitzpatrick/doc.improve-html-anchors

documentation: improve html anchors
Merge pull request #1126 from benfitzpatrick/doc.migration-reference

documentation: migration reference
Fixed cug PDF right margin overruns.
Document that implicit cycling is dead.
Removed obsolete documentation.
Updated previous.
Merge pull request #1128 from hjoliver/doc.follow-migration-ref

Document that implicit cycling is dead.
Merge pull request #1124 from hjoliver/integer-cycling-tweaks

Fixes a bug in integer cycling.
update