allow 'cast' for the JS target
Hyperlinks each proc and explains it is like map.
Adds each's map alias to index.
Adds documentation examples to sequtils.
Adds note about distnct being misspelled on purpose.
'importcpp' for the JS target to generate an infix call
Merge pull request #300 from gradha/pr_improves_sequtils_docs

Improves sequtils' docs
Merge branch 'master' of github.com:Araq/Nimrod