It took me a couple of minutes to scan
through the source code (of convert-ly.py) as Han-Wen suggested and find
the changes in 2.11.51, so as a convenience to others, here they are:
\\octave changed to \\octaveCheck
arpeggioUp changed to arpeggioArrowUp
arpeggioDown changed to arpeggioArrowDown
arpeggioNeutral changed to arpeggioNormal
setTextCresc changed to crescTextCresc
setTextDecresc changed to dimTextDecresc
setTextDecr changed to dimTextDecr
setTextDim changed to dimTextDim
setHairpinCresc changed to crescHairpin
setHairpinDecresc changed to dimHairpin
sustainUp changed to sustainOff
sustainDown changed to sustainOn
sostenutoDown changed to sostenutoOn
sostenutoUp changed to sostenutoOff
Funny thing is, the only ones I use
are the cresc and dim ones, and I don't see what was gained by those changes,
but no big deal - I'd have to look them up the next time used them anyway
most likely.