add Array#flatten
Merge remote-tracking branch 'origin/master' into tim/Array#flatten
implement Thread.recursion_guard (akin to MagLev and Rubinius) and use that in Array#flatten
add Dir.mkdir
Alias collect to map
add Array.try_convert
Merge pull request #341 from topazproject/tim/Dir.mkdir

Add Dir.mkdir
simpler assertion
Array#delete_at: Don't fail on negative indices
Array#delete_at: Fail on frozen
Add array/delete_at_spec.rb to Travis specs
Nitpicking
Merge pull request #344 from judofyr/array-delete_at

Implement Array#delete_at per RubySpec
Attempting to implement Kernel#sleep

which appears to work, but this is my first foray into RPython goodies.
Sleeping more than once, but for a smaller net time duration

although I'd like to be able to test the zero-arg case.  Not sure how to
do that without using a Thread or similar (?)
Handling the zero-arg case for Kernel#sleep
Adding self to AUTHORS per contribution guidelines :blush:
link the logs
Merge branch 'master' of github.com:topazproject/topaz
Revisions per feedback

including less float-casting tomfoolery, asserting allowed argument
counts, and returning something closer to the real amount of time slept
per the described `Kernel#sleep` behavior.