Using relative symlinks, fixes issue #1953
Bring back no name and simplify var merging
Merge pull request #1959 from jni-/mix_rel_symlink

Using relative symlinks, fixes issue #1953
Require arguments to be expanded to simplify relative symlink logic
Fix a couple of typos in the File module
Merge pull request #1976 from knewter/feature/file_module_doc_tweaks

Fix a couple of typos in the File module
Properly handle tuples in typespecs
Improve typespec docs
Remove old deprecated functions
Deprecate __FILE__ in favor of __DIR__ or __ENV__.file
Cache the environment for function definition

This speeds up compilation and reduces memory consumption. For
example, Ecto test suite consumes consistently 30% less memory
and loads 20% faster.