[ADD] website_forum: added new funtionality to post Articles and Discussions also on forum insted of only questions. On articles and discussions users kan post multiple reply on each post insted on only one reply per post and users will able to post reply on any other reply. in list posts will be default sorted by relevancy. show introduction message when people not logged in.
[ADD] website_forum: added demo data for article and discussion.
[IMP] improved code to use cookie instead of session to show introduction message and allow only 2 leval reply funtionality in discussion and article posts.
[IMP] better layout and options
[IMP] misc design elements
[IMP] misc layout improvements
[IMP] layout
Merge branch 'master' into master-forum-extension-tpa
[IMP] name is name (and not URL in case of links
[IMP] cleaning
[FIX] small bug
[FIX] sorting data
[FIX] forum
[FIX] website_forum: remove print
[FIX] load view from file shall not raise an exception

In --dev mode, when a view can't be loaded from the file in spite of
being referenced in field `arch_fs`, the current behavior is to raise
an exception. In most cases, developpers don't want the view to fail
so the behavior has been changed in favor of a logger warning and
a fallback to `arch_db`.
[FIX] website_mail: "save and continue" button
[TYPO] project_issue: efficiantly --> efficiently
[CLEAN] website_event_track: cleanind / migration to new api of the module
- removed event.tag and event.track.stage models
- cleaning / linting
- fixed kanban view of tracks
[IMP] Event: Split Tickets
Attendees are created on SO confirm.
Attendees are directly created for FREE registrations and
Attendees are created and SO are linked to the paid tickets.
Improved code to make (5 attendees lines, 2 SO lines) when 3 vip tickets and 2 standard tickets are bought.

This commit fullfills the following Goals:

Goal 1 : When only website_event is installed, free registration should be possible from website.
Goal 2 : When only event and website_event are installed, badge report should be print for free registrations.
Goal 3 : When website_event_sale is installed, at that time on confirming the sale order, the subscription line are splited per attendees.
Goal 4 : Added code for attendees registrations through SO. Now from SO also the attendee's details for the event can be filled same as from website