treemap: rm a bit of redundant code
update comments documenting issue #4492 workaround
add is_subset and is_superset to the Set trait
add is_disjoint to the Set trait
Add Felix Klock to AUTHORS
add difference and symmetric_difference to Set
add intersection and union to the Set trait
De-capitalize "note" to get rid of spurious tidy warnings
rustdoc: Remove structural records from tests. Fixes build breakage
std: Stop using oldcomm
Merge pull request #4682 from thestinger/treemap

Set trait improvements + minor treemap cleanup
Handle supertrait calls in default methods

Add a new method_super origin for supertrait methods. Also make
coherence create a table that maps pairs of trait IDs and self types
to impl IDs, so that it's possible to check a supertrait method
knowing only its index in its trait's methods (without knowing all
supertraits for a given trait).

r=nmatsakis and graydon -- with hope, we'll revamp all of this code as
per #4678, but for now this fixes the bug.

Closes #3979
xfail transitive inheritance test -- I guess this doesn't work yet
core tests: Add use vec; directive inside core::hashmap tests

This is probably to work around a bug.
librustc: De-export some of trans. rs=deexporting
librustc: Strdup unique strings instead of copying in byte by byte. Shaves 2MB off librustc at -O0.
librustc: Stop zeroing out allocas so much. Cuts 300K off librustc.
librustc: Speed up byte copy operations. r=nmatsakis
librustc: Long lines. rs=burning
Remove CFG_LLVM_CONFIG probe from configure script