Fix typo in README.markdown
remove special-case for 'main' from Pry.view_clip().
Revert "remove special-case for 'main' from Pry.view_clip()."

This reverts commit a56ac3f73dd375be208320b1f98c62a8cdfd5df7.

because, jruby.
cc @headius
add comment about special-case for jruby.
add Pry.main. cache its value.
update Pry.binding_for() to use Pry.main
update whereami command to use Pry.main (last one).
Remove support for 1.8-compatible versions of Ruby
Fix failing jruby spec
Fix default inspect for Ruby 2.1

In Ruby 2.1, the ancestor list of a singleton class includes the
singleton as the first element, so we need to filter it out.
Disable spec to work around rubinius/rubinius#2871
Merge pull request #1093 from pry/remove_mri18_support

Clean up support for Ruby 1.8