[Feature Request] Allow advanced keyword based filtering or even message altering

[vkedwardli]

Initial thought: Allow user to input provide a JavaScript function to filter/alter the message,
return false = don't send
return [String] where [String] could be the altered or original content

[vkedwardli]

A bit lazy to do the UI (since PSEditTextViewCell doesn't support dynamic height)

my current hard coded implementation: vkedwardli@b307d0e