Move functions of package common to main package
Rename main package to crypt. Rename Base64 function.
Rename variable 'cnt' (counter) to 'i'
Remove variables storing length from a byte since that data is implicit in the type
Remove variables storing length for the salt
Recovers package common
Change type of key to []byte
Use function len instead of a variable
Simplify function Verify
The salt parameter is also handled using []byte for better performance.