Fix a leak when convolution iterators are released before exhaustion.

This is an extremely succinct definition of convolution.
Obsolete import.
Logical ‘and’ function.
Logical ‘or’ function.
Better docs for REDAnd.
Map internally to REDAnd/REDOr.
Test REDAnd.
Test REDOr.
Adds a REDReduced wrapper class.
Early return from strict reductions.
Simplify.
I said simplify!
Early return from string reductions.
Early return from attributed string reductions.
Early return from enumerators.
Merge pull request #38 from robrix/early-returns

Early returns
Merge remote-tracking branch 'origin/master' into logical-operations
Early returning REDAnd without map.
Test non-short-circuiting REDAnd.
Early returning REDOr without map.