Accept mask name with Enter

[Paul Matthijsse]

Just a little request: when I name a mask, that name only shows up under Color Correction - Masks when I change the focus from the text entry field to another field (Inverted for example), the Enter key does not work here (as opposed to naming snapshots).

[agriggio]

masks: update the mask name when hitting enter

Fixes #98

→ <<cset fe2b315b80ac>>