Implement the active project feature

[hadronized]

We need to figure out:

• The user interface.
• Implement the code.

This feature allows to persistently (by using the config file) set a project name that will automatically be added to all the commands that might filter, and remove the “project column”. This will provide some kind of isolation of tasks.

[hadronized]

And again, don’t forget to update the initial RFC after deciding on the user interface.