Auto merge of #1311 - ebfull:cleanup-pp, r=ebfull

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.

src/zcash/JoinSplit.hpp

@@ -45,6 +45,8 @@ public:
 template<size_t NumInputs, size_t NumOutputs>
 class JoinSplit {
 public:
+    virtual ~JoinSplit() {}
+
     static JoinSplit<NumInputs, NumOutputs>* Generate();
     static JoinSplit<NumInputs, NumOutputs>* Unopened();
     static uint256 h_sig(const uint256& randomSeed,