Added tuple.__new__ accepting an iterable + tests

Support added to initialize a tuple using the tuple type class.  Allows
creation specifying positional or using the keyword argument 'sequence'.

Accepts iterables- tested with lists, tuples, sets, dicts and strings
Fix negative indexing issue.
Removed boxStrConstant, uncommented a few tests
Merge remote-tracking branch 'upstream/master' into runtime

Conflicts:
	src/runtime/tuple.cpp
	test/tests/tuples.py
Added dict.__new__ accepting list/dict + tests

Also fixed __getitem__.  Previously was using ->[key] which
would place a NULL value for the key if the key didn't exist.
Subsequent calls could segfault.
Merge pull request #125 from jvkersch/fix-tuple-indexing

Fix negative indexing issue.
Merge pull request #126 from chrisrammy/runtime_dict

Added dict.__new__ accepting list/dict + tests
Wow, I did not think that descriptors would apply here
Try to cut down the time of this test since it was sometimes timing out
Merge branch 'master' into capi5.1