drop is_not_empty from TreeSet/TreeMap
Handle divide by zero in constant evaluator
Merge pull request #4586 from thestinger/treemap

drop is_not_empty from TreeSet/TreeMap
Add is_mutbl field to arg
Parse `mut` in arguments
Add is_mutbl field to def_arg
Implement `mut` in arguments
syntax: Allow closure args to be mutable
syntax: Pretty-print `mut` qualifiers on args
testsuite: Add tests for mutable function arguments
doc: Document mutable function arguments
core: Rename to_mut and from_mut to cast_to_mut and cast_from_mut
doc: Document pattern matching on vectors
Merge pull request #4588 from sanxiyn/doc-mut-arg

doc: Document mutable function arguments
Merge pull request #4596 from Trinick/tomutrename

core: Rename to_mut and from_mut to cast_to_mut and cast_from_mut
Add Bill Fallon to AUTHORS
libsyntax: Implement the `+` syntax for multiple trait bounds. r=tjc
rename send_map to hashmap

This makes the module much more discoverable, and is in line with the
'treemap' naming.
get rid of the std::map::Map LinearMap impl

This legacy trait needs to be dropped in order to migrate to
core::container::Map, which doesn't require @ and Copy, and will make
proper use of borrowed pointers.
rename hashmap find/get -> find_copy/get_copy