Docs for decEq
More docstrings
Initial documentation efforts for effects
Annotate 'Lazy' with reason for laziness

i.e. is it just for evaluation, or is it for codata? This will be useful
for mixed induction/coinduction and allow the productivity checker to be
cleverer.
Merge pull request #989 from david-christiansen/docs

Docs
Merge pull request #991 from jfdm/doc/effects

Initial documentation efforts for effects
Merge remote-tracking branch 'upstream/master' into unifier-context

Conflicts:
	src/Idris/ElabTerm.hs
Add application context to all error messages

This makes it easier to find errors. It will also enable improved error
reflection soon.
Re-enable function arg error reflection

It now uses the same code path as normal error reflection.