insted of taking all integers from 2 to K, take only odds
since we know that the even prime is 2. This should in theory
reduce the time to check primilaty to half.
- Accept key generation size. (not practical above 64-bit)
- Decrypt from command args only for now
- Catch Unicode Decode Error cuased by wong key or size.
- Split into methods.
- Added a cli interface with commands 'gen <filename>' to generate keys
and 'encrypt <message> <publicKey>' to encrypt a message
to the passed key.
- Read and save keys.
