tigefa4u projects Trac

Improve the `separated` text presentation utility. By reversing the order of `(sep,item)` to `(item,sep)`, the output of `separated()` can directly be used in a tag builder.

FieldRefactoring: rendering of CC: field, taking into account the `[trac] show_email_addresses` setting and the EMAIL_VIEW permissions.

This was adapted from the initial patch provided by eblot on #5126.

FieldRefactoring: be robust when dealing with custom types which are no longer known.

TracTimeline API: the event links were broken in the RSS view of the timeline. Fix it by going in the direction of the ResoucerDescriptor / RenderingContext split of the WikiContext.

FieldRefactoring: rendering of textareas "(diff)" links is now also done in the controller, not in the template.

Also, as we needed to produce a link and couldn't do it in the `grouped_changelog_entries` method which lacked an Href object, we introduced a `rendered_changelog_entries` method on top of it.

FieldRefactoring: added support for rendering checkbox fields (value and diffs)

FieldRefactoring: use the ticket for retrieving the fields in order to minimize the calls to `TicketSystem(self.env).get_ticket_fields, and also put the dictionary of filed type by field names there (`ticket.types`)

FieldRefactoring: add link to milestone from the corresponding field in the ticket box (#449)

FieldRefactoring: refactor the rendering of a Milestone link

Triage: Direct the Update button to the correct place.