added tmp_vars for login + password_reset as replacement for hardcoded language non-neutral expressions

- Bugfix: changed "Return-Path: $form" to Return-Path: $from.

Bugfix: Spaces need to be deleted before cron save, because they are IGNORED on validation but lead to a non-functional cron.
Storing minute / hour / etc. values like "1, 23, 26" (with spaces) is allowed in validation and interface but leads to a BLOCKED crontab file and to non-functional crons of the whole web user.

This option can be enabled under System > Server config and is named "Web folder protection".

Implemented: FS#560 - Add support for APS (Application Packaging Standard)

Improved: FS#2131 - skip network reconfigure requests on mirror servers that are for a different server_id

Implemented: FS#2131 - skip network reconfigure requests on mirror servers that are for a different server_id

- Added Tipsy (http://onehackoranother.com/projects/jquery/tipsy/) so that one can create tooltips for additional explanations easily.

- Added check so that the client password isn't inserted into the message (for security reasons).

- Added circle access control so that 1) a reseller can create circles that contain only his clients, not all clients, and 2) a reseller can send messages only to his own circles instead of all circles.

- Added group (we call groups "circles" so that users don't mix them up with user groups) feature to client messaging section so that messages can be sent to either all clients/resellers or to groups of clients/resellers. TODO: add circle access control so that 1) a reseller can create circles that contain only his clients, not all clients, and 2) a reseller can send messages only to his own circles instead of all circles.