Better implementation of LinkedList.collect()

cf. 4fc8f75, da2dee5, ceylon/ceylon.language@81918e7, ceylon/ceylon.language#492.
Merge pull request #283 from lucaswerkmeister/fasterLinkedListCollect

Better implementation of LinkedList.collect()
fix up doc
some misc cleanup on Completable and Term
more cleanups
clean up some type expressions
clean up module doc
Merge branch '100' of https://github.com/mmusgrov/ceylon-sdk into mmusgrov-100
- port lots of Java code to Ceylon
- try to conform better with Ceylon API style
[transaction-100] ceylon port of DummyXAResource