Add pkg-config gc flags to llvm Makefile

This makes building work for systems which have gc installed in a
non-standard location.  The invocation was pulled from
https://github.com/schani/clojurec/pull/2, and then modified based on
https://github.com/idris-lang/Idris-dev/pull/428#issuecomment-26302460.
Send serialized versions of TT terms in pprint

This is the basis for commands that manipulate previously-output terms.
Update Network library

(Taken from @SimonJF's IdrisNet2 library at
https://github.com/SimonJF/IdrisNet2)
Fix implicit spotting in case blocks

When case blocks are in types we need to check which names are bound in
the case block, and not automatically bind them.
C99 fix
Shorthand syntax for default case alternatives

Instead of
   Just x <- foo | _ => bar

Can now simply say
   Just x <- foo | bar
Add commands for working with serialised terms

In particular, IDEs can now request the implicit and explicit versions
of previously-output terms. They can also request normalisation.
Send original terms in error messages

This allows IDE users to normalise terms or show implicits in errors.
Added experimental neweffects library

Simplifying effects API by removing 'm' parameter from Eff and leaving
choice of computation context to the Handler.
Fix idris.cabal
Remove oldeffects

(I forgot I hadn't done this already... but there's surely nobody still
using it!)
Fix idris.cabal properly this time...
Annotate displayed IDE metavars with original terms
Maintain pretty-printer bound vars

This means serialized terms, when normalized, will have correct colors
for bound variables.
Preserve bound var info across implicitness changes
Merge pull request #1315 from david-christiansen/serialized-terms

Serialize original TT terms, and annotate pretty-printer output
Merge pull request #1314 from WithHat/master

Removed Unicode character from source file
Unbreak windows build of idris_net.c
Add decision procedure for Prelude.Nat.LTE
Merge pull request #1319 from Melvar/decide-LTE

Add decision procedure for Prelude.Nat.LTE