Clearer usage example in readme.md involving Alice and Bob
Added new caching system for public keys to significantly increase speed of sequential message encryption/decryption using the same public key. Caching is optional but on by deafult, caches can also be cleared. Caches cost small persistent memory but save massive time and memory spikes.
Public key coordinates can now be accepted in a variety of formats in the order (x,y,curve) where curve is optional. The results will be converted to tuple coordinates (x,y) eventually as they are hashable and thus used in the new caching feature.