Added blake2 support
Merge branch 'master' into blake2, to get test suite fixes.
Delete mksum.test, which is redundant with signature.test
Bump version in docstring to 1.0.0
Clean up and add docs to signature.test
Add smoke tests for --help, --version
Don't mention bzip2, gzip in version as they don't actually work
Update file magic for BLAKE2
Ignore ctags file
Fix broken compatibility tests for MD4 mode.

rdiff sig defaults (temporarily) back to MD4, but gains an option to control
this. In MD4, truncate the hash the same way that previous versions did.

Add a sig_magic parameter to rs_sig_begin and rs_sig_file to let callers
choose a version.

Add NEWS about md4 weakness.
Mention CVE-2014-8242 in the news
Update THANKS
Passing strong_sum_len 0 to rs_sig_begin should select the hash's native
length.
Run tests that don't use canned signatures once for every hash algorithm
Remove stray line from .gitignore
BLAKE2 is the default for the rdiff command line.
Bump libtool version to reflect API changes.
Run signature.test (check canned signatures) for blake2 and md4
Don't use strerror string as a format template
Use rs_byte_t (unsigned char) for buffers to avoid signedness inconsistencies