* added a bunch of new command options to ls command, supercharging it. Using optparse.
* added options to show-method and show-doc
* now showing file/line for show-method, show-doc, show-command commands
* cleaned up 'help', and got rid of aliases from help display; now showing aliases in primary command help output.
* Added alias_command and desc commands to Pry::CommandBase
* Added pry and version tasks to Rakefile to start a pry session and show current version
* Added tests for alias_command and desc commands
* made it so ls_methods and ls_imethods return sort arrays
* made it so show_method without a paramater displays current method, if exists, who displays error if not
Changed tests to remove opts[:output] and then removed opts[:output]; replaced with output method, changed prompt in example_commands.rb to have a math* wait prompt. Added bullet points to examples in README.markdown. Added more info on TexPlay and Gosu for example_image_edit
* defined input/output accessors for Pry class to set global defaults for input and output (overridable by specific instances).
* Added reset_defaults method to set input/output and prompt lambdas back to defaults
* added output callback for 'cd' command
* changed eval_string += val to eval_string << val in Pry#r method, for performance reasons (no copy made with <<)