Missing icons in music shape

[Friedrich W. H. Kossebau]

Hi Marijn,

pushing for icon completeness, I found the music shape misses the following 
icons in the repository:

 music-clef-trebble
     plugins/musicshape/actions/SetClefAction.cpp:41
 music-clef
     plugins/musicshape/actions/SetClefAction.cpp:44
 music-clef-alto
     plugins/musicshape/actions/SetClefAction.cpp:43
 music-clef-bass
     plugins/musicshape/actions/SetClefAction.cpp:42
 musicflake
     plugins/musicshape/MusicShapeFactory.cpp:53
 musicshape
     plugins/musicshape/MusicToolFactory.cpp:33

musicflake surely would be the same as musicshape. No idea for a good icon 
here, guess not just a note, to be different from the icon for the 
SimpleEntryTool.

But all the clef ones surely are more easy to do. Do you just have forgotten 
to add them to the repository, or do we need to look into other music programs 
to copy matching icons (or even have to create new ones)?

Cheers
Friedrich

PS: There is no way to control the number of voices yet, or? The 
SimpleEntryTool just has 4 voices preset, without synchronizing to the actual 
part, which results in a crash if another voice is selected there.