Adding event filtering based on event content

I would like to be able to filter displayed event based on their content (typically a keyword in the title).

I developped two patches (one w.r.t. version 6.x-1.x-dev and one w.r.t. 7.x-1.0, both original archives have been taken from the module download page).

Changes (similar in both versions) are the following:

• Adding two additional configuration fields: filter_fields and filter_exp for specifying respectively the event fields to look at and a regular expression to be matched
• Additionnal debug information (lists event that filtered out because of contents)
• Add a function agenda_check_event_display which checks whether an event should be kept or not.
  
  One possible trouble is that this function uses the property_exists php function which requires php >= 5.1.
  This is only needed if the new configuration keys are not in the database (in case of an update).
• the actual event filtering then occurs in agenda_display_block
• configuration values in the example agenda

Additionaly, the version 7 patch includes the correction for the configuration url (Issue #954156: Module does not show up on Configuration menus).