Remove handling of even e in RSA keygen
Remove handling of even e in RSA keygen

This is a holdover from Rabin-Williams support and just confusing
in RSA-specific code.

webmaster128/botan,webmaster128/botan,webmaster128/botan,randombit/botan,randombit/botan,webmaster128/botan,randombit/botan,randombit/botan,randombit/botan,webmaster128/botan