Colorful tasks and calanders

[karlfrohlich]

Is your feature request related to a problem? Please describe.
Sometimes it is hard to distinguish between tasks and meetings, and make sense of all my many todos.

Describe the solution you'd like
Ability to choose color for...

1. each different imported calander (essential)
2. upcoming tasks (nice to have)
3. past due tasks (nice to have)
4. tasks from a certain filter criteria (contains some characters, from a certain file, etc) (nice to have)