[FIX] Query passphrase cache with secret key ID

- Before each public key encrypted packet key id was used
  to check against a list of public keys if such a public key
  exists and if it did, it was used to check against the passphrase
  cache, if the passphrase for that key was already in the cache.
  That doesn't make any sense at all, instead the list of secret keys
  has to be checked against the public key id.
Add some new test cases.
Ignore MLHeaders folder.
Add method converting LF to CRLF.
[FIX] FlippedView message is no longer shown in Console.
[FIX] Signatures are no longer accumulating in Signature view.
Correctly copy blocks.
Update project file to reflect Libmacpg.xpc name.
Forgot to add this.
Removed submodules.
Make sure Dependencies directory is created.
Don't accumulate signatures.
Merge branch 'experimental' of github.com:GPGTools/GPGMail into experimental