clean up cancellation header docs
Make +nameForType: a class method
Dynamically patch NSURLCredentialStorage for storing SSSH credentials
Support for retrieving default SSH credential
Correct format string
Fixes 32bit builds
Use libcurl's error output for NSLocalizedFailureReasonErrorKey too
Use curl_easy_strerror() for error failure reason

Not quite ideal, but seems closest parallel libcurl has
Persist private key passphrases too
Removed executable flags from some source files.
Removed outdated built documentation. Comments are in source files anyway.
Removed the manifest file.
Removed dev notes.
Removed CURLHandleTester.
Removed pre-built libraries.
Removed external libraries build scripts and instructions.
Removed references to external pre-built libraries from project file.
Merge remote-tracking branch 'upstream/sam/async'

Conflicts:
	SFTP