remove const specifiers from return values in DataStructs
add initial pass at query-query matching for Atoms and Bonds
fix and test for sf.net issu 2738320
add Mol.AddRecursiveQuery() method to Mol
http://sourceforge.net/tracker/index.php?func=detail&aid=1968930&group_id=160139&atid=814650
In order to fix the problem, the value of the query function for atomMass queries
is being multiplied by a constant factor (currently 1000) before converting
to an int. This allows distinguishing between things like [CH4] (where the
C has mass 12.011) and [12CH4] (where the C has mass 12.000).