addBiopaxInstance: This function adds a new instance to an existing biopax model.
Description
This function adds a new instance to an existing biopax
model. "properties" is a named list of vectors, with the
vector name as the name of the property and every entry of
the vector a property value. Please note: case sensitivity!
In Biopax Level 2 all properties are written in all capital
letters. This will change in Biopax Level 3.