[IMP] web_menu_navbar_needaction: Several improvements:
* Make the menu reflow after updating needactions
* Allow to disable needaction completely or to set a custom domain
* Support for clicking the number to end up on the first action
* No need to block the UI for our request
* Don't crash on corner cases, filter out search defaults from context, disable custom filters
* Allow to define needaction domains for any menu
* Support server actions
* Support models implementing the function, but not the interface
* Show a main menu's child needaction counters
Holger Brunn