Initial pry handling
Make the taking over process the evaluator
Test IEx.Server start options and configurations
Keep IEx helpers around for pry
Add IEx.Helpers.respawn
Extract IEx.Evaluator to its own process
Make ExUnit autorun configurable
Move booting process to IEx.Server and allow take over
IEx.Server.boot -> IEx.Server.start
Improve IEx.Server coverage
Merge pull request #1761 from elixir-lang/jv-pry

Provide IEx.pry functionality
CHANGELOG and doc typos (thanks @ericmj)
Set ExUnit color based on IO.ANSI.terminal?, closes #1756
Do not block the client if take is refused in IEx.pry
Ensure Stream.flat_map does not intercept wrapped lazy enumeration