unwrap: Add a function to find residues for phase unwrapping.
unwrap: Expand test for find_phase_residues.
unwrap: Implemented setup for branch cuts.
unwrap: Implemented branch cuts.

Tests for small images with wrap around and no masked entries seems
promising. The branch cut core should be ready for masked images and
image borders, but this has not yet been implemented in the setup logic
that defines the problem.

Included with these changes are a queue implementation in C
(the files queue.{c,h}) which is part of the c-algorithms library,
copyright Simon Howard and released under the BSD-like ISC license.
unwrap: Add masking and borders to find_branch_cuts.

All features are now added. Tests for masked images and images without
wrap_around needs adding.
unwrap: Implement residue calculation from masked arrays.
unwrap: Rename func ...goldstein -> ...branch_cuts.
unwrap: Move private functions to top of file.
unwrap: Docstring for unwrap_phase_branch_cuts.
unwrap: Docstring for find_branch_cuts.
unwrap: Remove unneccesary parameters.
unwrap: Implement phase integration.
unwrap: Differentiate between edge and cut coordinates.
unwrap: Fix bug in edge coordinates.
unwrap: more debug output
unwrap: Comment out debug output.
unwrap: Minor cleanup in cython code.
unwrap: Bugfix cut detection logic.
unwrap: Cleanup in cython code.
unwrap: Comments for skip-along for edges.