Working per filter case senitivity

This version has a per filter case senitivity option, so that you can set the case sensitivity option on a per filter base instead of global (and thus for each user).

Also the following little items have been worked on since the previous release
Updated english with missing translations
Finished the work on the case sensitive per filter option

V1.0 by eagle00789

This is the first release by eagle00789.
This version is based on version 2.1.2 from the original creator and has the following changes made to it:

• Show message after a mail has been process by a filter
• Make use of an external config file for the configuration of the plugin
• Use the internal roundcube structures to make use of a config file.