Reverting to earlier implementation TypeReflection::isAssignableFrom
Reverting to earlier implementation TypeReflection::isAssignableFrom

Implementation based on RootCollection iteration segfaults in some
cases.

Indicates a bug in RootCollection - to be fixed later.

aguetlein/databricxx,oschulz/databricxx,oschulz/databricxx,aguetlein/databricxx,databricxx/databricxx,databricxx/databricxx