Merge branch '1.2.x' into 1.3.x
* 1.2.x: (89 commits)
t/: Add a test suite.
ec.c: Don't lose error status when constructing points from a sequence.
ec.c: Free partially constructed points coordinatewise.
*.c: Be more careful about `PySequence_Size'.
key.c: Reformat the rest of the `KeyError' constructor.
key.c: Parse `KeyError' constructor arguments by hand.
catacomb-python.h: Add a macro for raising `OverflowError'.
key.c: Collect `KeyError' argument count as a separate step.
key.c: Use tuple functions on `KeyError' argument tuple.
key.c: Rename sad-path label to `end'.
key.c: Delete duplicate setting of `errstring'.
util.c (mkexc): Populate dictionary before constructing exception class.
key.c: Only set the error code.
catacomb.c, util.c: Publish negative constants correctly.
field.c: Delete the completely unused `getfe' function.
key.c (convfilter): Fix sense of error tests.
buffer.c, ec.c: Fix required size for EC `buffer' encoding.
algorithms.c: Fix `max' property name in docstrings.
catacomb/__init__.py (_HashBase): Check that integers are within bounds.
debian/rules: Build using the provided Makefile.
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