[filter] Save the filters created

[alacasta]

What?

As a user, i want to create filters and their rules (i.e. colour) once and restart them in another dry-run to not need to rebuild such rules over and over again.

Remark This feature can be enabled after analysing #56

How?

It should be possible to access to this feature like

• Having a new entry like File > Save Filters... to save the current filters set
• Having a new entry like File > Load Filters... to load a saved filter configuration

They can be stored in the same place like the connections so far.