Merge branch 'NullPtr' of https://github.com/eamsden/Idris-dev into NullPtr
null primitive for the Java back end
Make test033 work with Java by using nullPtr from prelude instead of c function
Add test documentation
Fix LLVM codegen of negative integer literals
Added instructions for LLVM and LibFFI by default to README
Add example of custom.mk for building with both optional dependencies
Add note about custom.mk example
Merge pull request #601 from Ralith/fix-negative-ints

Fix LLVM codegen of negative integer literals
Change reg016 to test big int literals properly

Fixes #604
Merge remote-tracking branch 'upstream/master' into readme-llvm-ffi to fix reg016.
Merge branch 'master' into NullPtr
Merge pull request #603 from david-christiansen/readme-llvm-ffi

Update README with info about optional dependencies
Merge pull request #594 from JanBessai/NullPtr

Null ptr