This change was necessary to fix the crypto on Android, where SpongyCastly must
be used instead (because of classloader conflicts). The new ECUtils class
contains the remaining code that could not be made provider-agnostic. In
particular, the EmailDestination format for EC requires the use of BouncyCastle
point encoding.
The full BouncyCastle library is now bundled, because it must be added as a
Security Provider to use the JCA system, and this requires a valid signature.
JCA is used for AES operations instead of I2P's built-in AES engine because the
PKCS#7 padding class could not be accessed on its own in a provider-agnostic
manner. The resulting code is also cleaner.
