Start a user contributed script repository

This should depend on a redesign of the base engine.
- I'd like to see .tar.gz files containing a structure of config files, scripts and graphics files for every "add-on"
- Add-Ons should install either system-wide or per user, both being possible
- Events should be rewritten as such:
  - you select a device (e.g. phone1), a relation (stays within, leaves at least), a range (in the usual scale), an interval (eg 5 secs) and finally the actions to take place
  - actions should be selectable from the list of add-ons with icon
  - each add-on may define a list of actions
  - an action may have configurable parameters
  - add-ons should have a script to detect usefulnes on a system - no need to show an add-on for xmms if no xmms installed, show a switch to override this filter
  - add-ons should have an update url or be marked as updated via package manager (for system-wide add-ons)
  - add-ons should have a clear translatable description and an add-on icon
  - actions should also have a clear translatable description of the use and all parameters and an action icon
- user-specific installed add-ons should be regularly checked upon updates
- the list of events should show the configured actions in a nice table with Device >|< n dist m secs + a subtable with all actions showing the add-on icon, the action icon and the action short description

The aim should be an add-on system that is easy to use as a novice user, leaves all flexability for experienced users and makes add-on development very easy. Add-ons should be canned into a new package depending on blueproximity.