Optimize search for PGP markers, on advice from Instruments

- very noticeable speed improvement, particularly on large attachments
- searches for "-----END PGP..." should not start from position 0; instead
  continue search after the "-----BEGIN PGP..." position
- attachmentMightBePGPEncrypted and attachmentMightBePGPSignature are
  folded into one search to avoid redundancy
- as before, only "pgp", "gpg", "asc", and "sig" are recognized
  extensions; but the previous code was doing an unnecessary search for
  a PUBLIC KEY BLOCK in every type of file
- do not do redundant conversions from NSData to decoded strings
- add unit tests to validate changes--with a BundleTestRunner app to
  load GPGMail.mailbundle

- post-build script tells Mail to save and quit
Add helpful tooltips for first time users.

- Explain the problem and offer a possible solution.

[#304 state:fixed]
Merge branch 'master' of github.com:GPGTools/GPGMail
Version and Build text is selectable.

[#476 state:fixed]
Make german translation stick

Yes Lukas, you need to actually edit the .strings file! DOH!
Show warnings for not existing selectors!
Fix warnings!
Cleanup of the start up routine

- Also fix the NSImage warnings
Fix a Mail.app hang caused by nested dispatch_once
Complete inline attachment implementation

- Display an appropriate error message in the message view if verification
  or decryption of one or more attachments failed.
- In PGP Attachments view display the appropriate error message for each attachment.
- In PGP Attachments view display a success message if the attachment was only encrypted
  and succeeds to decrypt.
- In PGP Attachments view display the verified and decrypted icons at the right position
- Remove .sig file from message view if the attachment verified.
- Introduce devel option HideAllSignatureAttachments to remove the .sig file also if verification failed.

[#445 state:fixed] [#69 state:fixed] [#283 state:fixed] [#266 state:fixed] [#408 state:fixed]
Remove extremely dangerous NSAsserts

- which are not needed at all either.
Update GPGMail Preferences to use sharedOptions

- Added an a method which returns [GPGOptions sharedOptions] to
  avoid creating a new GPGOptions object.
Increase alpha version for the last time :)
Correctly return encrypted data if decrypting fails.
HeadersEditor NSRangeException fixed.
Anything added.
fixing error that hides the uninstaller window after running it from a downloaded dmg
Merge remote-tracking branch 'upstream/master' into PGPmarkerSearches_201203

Conflicts:
	Source/MimePart+GPGMail.h
	Source/MimePart+GPGMail.m
Support non clear signed messages

- Fix the part PGP markers for signed messages.

[#191 state:fixed]
Merge branch 'master' of github.com:GPGTools/GPGMail