- Fixed PHPDoc
- Fixed the runtime template cache
- Fixed coding styles
- Changed preg_match to strpos for better performance

- Added static runtime cache

- Added JS confirmation before sending the email
- Added a hidden field for better distinguishing the preview emails (there was a fluid bug)
- Added an extra groupBy to avoid sending multiple emails to the same recipient

Fixed:
- preview markers in the newsletter
- keep values in the newsletter form after sending
- fixed pagination performance in MailQueue

Sending to subgroup members
Markup changes

[FEATURE] Add Mail Layouts

See merge request !17

[BUGFIX] Fix global variable name in README

See merge request !16