Added myself to contributors
Added "if_valid" syntax rule for possibly failing Effects

Allows branching based on whether an effectful operation returning
Either l r succeeds (l failure, r success) and updating the resource
accordingly.
Merge pull request #541 from ahmadsalim/feature/mecontributors

Added myself to contributors
Update CHANGELOG
A bit more syntactic sugar for effect testing

May read better in many contexts.
Added 'implicit bind' syntax

Intuitively, !f x y, means that 'f x y' should be bound before the call
(using >>=). Implicit binds can be nested.
Change implicit bind notation to a postfix !
Convert IO errors into erros in the Idris monad

Introduces a variant of liftIO, called runIO, that converts IO errors into
Idris errors with the Msg constructor.

Fixes #543.
Merge pull request #544 from david-christiansen/issue/543

Convert IO errors into erros in the Idris monad
Merge branch 'master' of github.com:edwinb/Idris-dev into implicit-bind
Check for file extension in :e

Now, when Idris is invoked without a module file extension, :e will add it.

Fixes #526.
Merge pull request #545 from david-christiansen/issue/526

Check for file extension in :e