Add DTCP encryption support via an optionally-enabled output filter.

Note: entire contents of file are read into memory in order to encrypt in a single call
Contents are chunked transfer encoded

New module configuration settings:

 - DTCPEnableDTCPEncryption on/off (case sensitive)
   If on, encrypt content using the "DtcpEncryptFilter" output filter
 - DTCPEncryptionPort portNum
   Specify the DTCP session listening port