v4: Add support for per-ticket projects

[cweiske]

This allows "small" projects to be tied to a ticket number instead of a Jira ticket prefix. Subtasks and tickets within epics are seen as subtickets, and the project is automatically selected when using such ticket numbers.

Example:

• TT project "Hack" with Jira prefix "HACK"
• TT project "Hack Monday" with Jira ticket "HACK-23"

When booking onto "HACK-14", project "Hack" will automatically be chosen. When booking onto "HACK-23" or a subticket, "Hack Monday" project will be chosen.

Based on PR #76 - merge that first.

[CybotTM]

Thanks, but I cannot merge due to conflicts.

[cweiske]

I rebased manually and had no problems. Try again with my force-pushed branch.

[CybotTM]

Thanks.