Merge pull request #5 from 013/master

Added :s substituion, thanks to 013
Made the :s functionality work on a per-channel basis
Made message substitutions work with /g flag
fixed range on :s/ messages blame 013
Fixed 'unexpected end of pattern'

Fixed 'unexpected end of pattern'
Merge pull request #7 from 013/patch-2

Fixed 'unexpected end of pattern'
really fixed unexpected end of pattern
Updated the README file to reflect the changes for the :s functionality.
Uncommented the code that searches for messages once :s/ is invoked based on channel
Fixed BigBen from dying with an invalid replacement