Performance: store NoteBase UIConfiguration colors between config changes.

Performance: store NoteBase UIConfiguration colors between config changes.

Cumulative time in percent while wiggling the tempo lines rapidly.

Before:

MidiRegionview::update_sustained 12.02

 NoteBase::base_color             6.43
 MidiGhostRegion::update_note     3.12
 Note::set                        1.27
 TempoMap::frame_at_quarter_note  0.59
 _dynamic_cast                    0.13

After:

MidiRegionview::update_sustained  10.49

 MidiGhostRegion::update_note      5.57
 Note::set                         2.52
 TempoMap::frame_at_quarter_note   1.13
 NoteBase::base_color              0.17
 _dynamic_cast                     0.17