This is because they may conflict with reserved names. Also took
this opportunity to make the guards in the zcash subdir a bit
more uniform by having them all conform to ZC_<...>_H_
This closes#1272
Deallocate the public parameters during Shutdown.
This also has it deallocated in `GenerateParams` and `test_bitcoin`. The virtual destructor probably isn't necessary but I added it just in case we need it some other time.
CPourTx structural changes
* Enable binary serialization of proofs and the proving key (closes#799) and make the proofs fixed-size.
* Reorder fields of CPourTx to match the spec (closes#927)