Merge pull request #362 from PeterBjuhr/master

MusicXML export development
add beatstructure to time command
fix import scheme when HOME environment variable is not defined
add ukulele and missing tunings as per issue #342
add custom string tuning entry to all the plucked string instruments

TODO: test all instruments and remember entered values using a completion
fix Banjo
upd chlog
save completions in scorewiz plucked strings
smart do-it-all function
new builtin snippet to double current line or selection (issue #340)
improve behaviour: when c-d is pressed on empty line, content of previous line is copied
wip regen all symbols with LilyPond 2.18
better slashed grace icon
all symbols regenerated with lilypond 2.18
5 new barline icons
new barline types (fixes #365)

todo: fix kievan icon
fix barline kievan icon
add markup \\oval
rel import in ly
simplify socket naming. todo: test on windows