fix Java warnings in com/freiheit/gnupg
jni: LC_MESSAGES might not be defined on WIN32 or other platforms
gpgme needs LD_LIBRARY_PATH set since it launches cmd line progs like gpg2

gpg2 is dynamically linked, and the only way in Android to find a dylib is
via the LD_LIBRARY_PATH.  Therefore, the gpg lib dir needs to be added
for gpgme env as well.
only use LD_LIBRARY_PATH code on Android
fix the listkeys feature of the gpgme library
gnupg-for-java: expose all booleans in gpgme_key_t as Java methods
remove unneeded autogenerated JNI headers

I think this are only used for C++, but right now they are just another
file to maintain while providing no benefit to us.  They can be updated in
the gnupg-for-java project once development settles down.
gnupg-for-java: add GnuPGKey.hasSecretKey() to report if any subkey is secret
gnupg-for-java: fix compiler warnings
gnupg-for-java: also allow fetching secret keys using GnuPGKey contructor

Before, it would only search and return public keys
allow fetching secret keys using GnuPGContext.getKeyByFingerprint()
add listSecretKeys() and searchSecretKeys() to GnuPGContext
simplify and complete get/set for Armor and TextMode
add GnuPGData.size() to improve ByteArrayOutputStream performance

Since ByteArrayOutputStreams are used to get data out of GnuPGData, add a
size() method so that the ByteArrayOutputStream can pre-allocate the memory
needed, or at least close to the final number.
add javaish encryption methods
sync up trivial changes from gnupg-for-android
include signature notations in key lists
put gnupg libs first in LD_LIBRARY_PATH to make sure we get the right ones

this should make it a tiny bit harder to sneak a bad .so into gnupg, and
also avoid cases where people might install stuff willy-nilly on their
device.
standardize layout of public method declarations for clarity

I want to be able to rapidly scan the methods and see how the args differ.
fix gpgmeOpEncryptSign method signature in Java