Document -X at command line

Now we can close #593.
Add some file functions

popen, pclose, fgetc and fflush
Merge pull request #908 from david-christiansen/ext-help

Document -X at command line
Merge branch 'master' of github.com:idris-lang/Idris-dev
Better environment management in unification

Also properly guard !!s so that if there is a scope error, you get an
error message rather than a crash (though no guarantees the error
message will be much use...)

Fixes #738, #600 and #891 (and possibly more...)
Support explicit namespaces in IDESlave :type-of
Add IDESlave command for getting documentation

This is used by Emacs to get documentation for the symbol at point.
Merge remote-tracking branch 'upstream/master' into ideslave-explicit-namespaces
Add missing output annotation serialization to ideslave
Merge pull request #910 from david-christiansen/ideslave-explicit-namespaces

IDESlave improvements: namespaces and docs
javascript: use %include directive to include external javascript files
updated CHANGELOG
Enable refinement by infix operators in prover

Fixes #873.
Merge pull request #914 from raichoo/javascript

javascript: use %include directive to include external javascript files
Merge pull request #915 from david-christiansen/issue/873

Enable refinement by infix operators in prover
Proof search fix
Tinker with popen/poll
Port Haskell's Bounded class

This is useful for avoiding magic numbers.
Split Bounded into lower and upper bound type classes
Total order on Nat