40091 double accidental chords

Use "native" glyphs from chord symbol text style font for double flat/sharp, rather than forcing all chord symbols to use MScore Text.  Also adds those glyphs to MuseJazz.  For now at least, it appear the same version of MuseJazz might work on all platforms.  At least, the version I built (on Ubuntu, using 2012 version of FontForge) works for me with kerning on Ubuntu using the options that formerly only worked on Mac.  We will need to test this in "official" builds on all platforms, though.