Negative counts reverse the shift direction
Thread additions, Mutex and Queue

Thread.list reports itself as the current thread, and Thread#new
explicitly disallows creation of threads.

Thread now supports the fiber- and thread-local variable storage
interface

Mutex and Queue are implemented, and behave as expected, given the
single-threaded environment.
Fix String#to_proc
Remove spec/filters/bugs/symbol.rb

These bugs are fixed by c71b6c
Silence output using IO#write_proc=
Autoclone gh-pages repo when building docs
Fix yard version
Add corelib/stdlib respective READMEs
Make the Opal Tilt template work in any context.
Removing giant if statement

Good call ella.
Use require_paths from spec
Merge pull request #551 from yhara/fix_to_proc

Fix String#to_proc
Merge pull request #573 from kylekyle/use_gem

Use require_paths from spec
Merge pull request #570 from kylekyle/tilt

Make the Opal Tilt template work in any context.
Update dependencies

Opal requires Hike and a version of Sprockets that support Sprockets.register_engine
Specify sprockets version

Changed from >= 2.12.0 to ~> 2.0 a la ella.
Refactor Kernel#singleton_class

Removed dead branches, removed duplication.
Keep runtime initialization in a single place
Cleanup code layout of runtime
Expose bridged classes list