Pull common named thread factory code out into new concurrent.clj
Move lab_test to mirror test restructuring

Commenting out the lab test as it's no longer completing successfully, will replace when it's fixed but shouldn't block other work
Merge branch 'master' of github.com:clojure/core.async
split out some cljs tests, fixed some compile errors, basic alt tests
cljs alt! tests pass
added try/catch/finally to cljs
remove some debug calls
Fix race in multiplexing, dispatch handlers

Because of the recur points in the impl, alt and take handlers can
occur in the dispatch pool (after a source dries up), in which case
returning the gotten val will just disappear. Make sure to run handlers.
refactor source to make Maven happy
fix file suffix for cljs files
Fix race in callback test
use let instead of nested fns in gen-plan. Results in cleaner code/debugging.
fix for fns called as the first element of a sexpr
add skip-wiki meta to hide impl in autodoc
Alter the next execution block *before* possibly dispatching!
Add initial examples
add walkthrough examples, still a wip