Improvements to 'make check'

* 3f141e4 : Makes it easier to extract the needed plaintext and ciphertext buffer lengths by dummy calls to ntru_crypto_ntru_encrypt/decrypt. You previously needed to pass a plaintext to encrypt even if all you wanted was the size of the buffer needed to hold a ciphertext. Same with passing a ciphertext to get the plaintext length. Both values are fixed by the parameter set and do not depend on the passed plaintext or ciphertext.

* b09468a : Exposes interface for getting a human readable parameter set name from a param set id
* 6083c6b : Makes 'make check' print param set names and also respect public/private interface boundary