Output: Use throwError from Control.Monad.Except

Update 'Idris/Output.hs' to use 'throwError' from 'Control.Monad.Except'
rather than from 'Control.Monad.Error', which causes the build to fail
with a default setup:

  src/Idris/Output.hs:18:1: Warning:
      Module ‘Control.Monad.Error’ is deprecated:
        Use Control.Monad.Except instead

  <no location info>:
  Failing due to -Werror.

With this patch it should build fine.

This requires mtl >= 2.2.1, so add this to the cabal file.

Signed-off-by: Alexander Berntsen <alexander@plaimi.net>
Add proper namespace to class instances

Fixes #1779
Remove -Werror in Output.hs due to ErrorT

As far as I can tell, we can't replace ErrorT with ExceptT yet because
there's a missing MonadException instance in Haskeline. Also, the
dependencies we have set are causing a build failure on travis due to
the -Werror.

Proper fixes welcome! This is noted in issue #1780
Updates to idrislang.sty
Work around bug in glibc 2.11
Several updates to idrislang.sty

+ Removal of numbers package option. Listing styles must be set either globally using `\lstset{}` or per code or listings environment options.
+ Addition of a beamer style.
+ Inclusion of the `:pprint` LaTeX formatting commands. No more need to copy everything from the result of `:pprint`, just the code snippet.
  + command chars for fancy verbatim has been set globally.
+ Option to change spacing command, useful for cases where line spacing is changed via different commands. For example: memoir has `\SingleSpacing`, setspace has `\singlespacing`.
Look in binders when building size change graph

Fixes #1781
Support for inductive-inductive types

Add constructors to context immediately after elaborating, rather than
adding the whole data type at once, so that later constructors can use
them. Fixes #1757.
Merge pull request #1783 from jfdm/contrib/updates

Updates to idrislang.sty
Merge pull request #1782 from mietek/master

Work around bug in glibc 2.11
javascript: better unicode support
added optimizations to js/node cabal section
updated CHANGELOG
Merge pull request #1785 from raichoo/master

javascript
Fix visibility of imported things

Fixes #111
Previously, if a module B imports a module A, then a module C imports B,
the public names in A would also be visible to C (i.e. B would
automatically reexport everything from A). This seems to be a bad
default.

This patch changes the default behaviour so that the only names exported
from a module are those defined in that module. If B imports A and wants
to reexport everything in A, then A should be imported with the "public"
modifier (i.e. "import public A").

Several changes have been made to the prelude, since several prelude
modules were taking advantage of the old broken behaviour.

This may cause lots of things to break. Sorry. The fix is typically just
to import the module you should have imported anyway :).
Merge branch 'master' of github.com:idris-lang/Idris-dev
Update CHANGELOG
Fix doc build
Merge pull request #1749 from alexander-b/fix-build

Output: Use throwError from Control.Monad.Except
Implemented @-patterns

By popular request. Fixes #1706.

It's not the most efficient desugaring, merely translating the @s on the
left to lets on the right, so the case tree builder won't be aware of
it. Still, it provides the notation and it works nicely with showing
what is in scope and what is available in the prover and so on.