imported version with virtual mass

should have no influence unless you add the line

ps.virtualmass = True

at the beginning of your gh definition
merged constraints and virtual mass

still problems with line constraints
finer debug on constraints using virtual mass

rail constraints still not working
tried modifying the virtual mass def for spring

no luck
new version by paul
taken python code out of GH definition
Merge remote-tracking branch 'origin/distrib'