- added TrustWord DB in assets
- added GPG external build based on gnupg-for-android external build
- added runtime asset unpacking into file system, for native access
- added gradle tasks and dependencies to invoke external and pEpEngine build
- added GPGAgentService and associated android intent to start gpg-agent
- added dumb pinentry.sh to keep gpg-agent happy
Note : temporary added import_key to basic_api for testing purpose