Bugfix for #1070 - odbc columns not cleared.
Bugfix for #1070 - odbc columns not cleared.

I suspect that this bug is due to a change in the ODBC implementation:
old column values are no longer being cleared, and thus, they contain
left-over garbage. So, explicitly truncate the garbage.  This fixes
a crash described in opencog/atomspace #1070

inflector/atomspace,inflector/atomspace,ArvinPan/atomspace,ArvinPan/atomspace,yantrabuddhi/atomspace,yantrabuddhi/atomspace,rTreutlein/atomspace,AmeBel/atomspace,AmeBel/atomspace,rTreutlein/atomspace,rTreutlein/atomspace,AmeBel/atomspace,AmeBel/atomspace,rTreutlein/atomspace,misgeatgit/atomspace,inflector/atomspace,misgeatgit/atomspace,misgeatgit/atomspace,rTreutlein/atomspace,yantrabuddhi/atomspace,misgeatgit/atomspace,AmeBel/atomspace,ArvinPan/atomspace,yantrabuddhi/atomspace,inflector/atomspace,misgeatgit/atomspace,yantrabuddhi/atomspace,inflector/atomspace,ArvinPan/atomspace