operations no longer require two distinct BN_CTX structures. This may put
more "strain" on the current BN_CTX implementation (which has a fixed limit
to the number of variables it will hold), but so far this limit is not
triggered by any of the tests pass and I will be changing BN_CTX in the
near future to avoid this problem anyway.
This also changes the default RSA implementation code to use the BN_CTX in
favour of initialising some of its variables locally in each function.
override key-generation implementations by placing handlers in the methods
for DSA and DH. Also, parameter generation for DSA and DH is possible by
another new handler for each method.
to be prefixed with e_ instead of hw_. They aren't necessarely hardware
engines. The files commited here are exact copies of the corresponding
hw_ files found in crypto/engine/.
