Matching Blocks World Domain
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This is a simple variant of the blocks world where each block is
either positive or negative and there are two hands, one positive and
one negative. 

The twist is that if a block is picked up by a hand of opposite
polarity then it is damaged such that no other block can be placed on
it, which can lead to deadends.  The interaction between hands and
blocks of the same polarity is just as in the standard blocks world.
