#15 Atom expression fails for amidine in protonation model

[Joerg Kurt Wegner]

SMARTS parser fails for

#guanidine or amidine
# causes problem in SMARTS parser
#TRANSFORM [#6^2+0:1](=[N^2+0:2])(-[N^2]) >>
[#6+:1](=N-:2)(-N)

See also protonation model and tranformation rules in class
BasicTransformationRulesHolder