WISH: implement crypt scheme

[Oldes]

In Rebol2 there was a crypt scheme -> http://www.rebol.com/docs/encryption.html

In Rebol3 there are available several encryption options already (mostly to be able have a tls port), but these are across multiple functions (rsa, rsa-init, aes, rc4). It would be nice to have it unified and possibly compatible with Rebol2 again.

[Oldes]

The crypt port is now almost done ---> Oldes/Rebol3#45
Usage example may be found in the test-crypt.r3 file or in one of crypt related unit tests.

There are still some natives like (rsa, rsa-init, rc4) floating around, but I need to take some rest of it.

[Oldes]

Here are my results from the mentioned test-crypt script (running on notebook on battery only)