Improve error for untyped member definition
Add error for missing class instance members
Improve "error in type class" message
Merge pull request #363 from garyb/class-errors

Improve class-member related errors
Fix Haddocks
Bump version
refine syb dependency

to combat `cabal install purescript` failure:

src/Language/PureScript/TypeChecker/Types.hs:48:9:
 Module `Data.Generics' does not export `everythingWithContext'
Merge pull request #364 from dckc/patch-1

refine syb dependency
Update RELEASE-0.5.md
Update RELEASE-0.5.md
Fix Show String instance
Added `null` to reserved words.
Merge branch 'master' of github.com:purescript/purescript
Merge pull request #366 from joneshf/master

Added `null` to reserved words.