update the statement of testing if a handler is a list or tuple
Add hooks for HTTPClient and HTTPConnection customization.
digest authentication
Optimized StackContext implementation
Comparison fix
Fix escaping error in blog demo

Closes #726.
Use range instead of xrange
Don't use range for performance reasons
Ignore negative return values from CurlMulti.timeout.

pycurl has a wraparound bug that can turn very large timeouts into
negative numbers.

Closes #712.
_handle_exception in testing.py ignores passed exception
Parse if-modified-since timestamps without going through time_t or local time.

This fixes a bug on windows in which mktime cannot work with times before
the epoch.

Closes #713.
Merge remote-tracking branch 'mrjoes/perf'
Merge pull request #700 from icaromedeiros/master

Digest authentication for curl_httpclient
Document the fact that auth_mode="digest" only works with curl.

Add check in simple_httpclient that only basic mode is used.
Merge pull request #693 from apieceofredcloth/master

Allow lists as well as tuples in handler definitions
Handle malformed headers more gracefully.

Closes #699.
Merge commit '0771f'