text.Shaper is not thread safe, which caused crash when adding
multiple VSTI plugins to a DAW project. This change fixes that
crash. Further refactorings need to consider where that text.Shaper
should actually reside.
The keyboard shortcuts were too wonky, so removed them altogether. Had to remove also unit wrapping from model (now it just clamps the parameter to the current units) as it did not play nice with the new editor.
Closes#70.