Rank-filter

* Handle window center outside of `for`-loops. 159

* Support Python 3.7. 152
* Store first rank value in destination at beginning. 154
* Use prefix operators for increment/decrement. 155
* Add missing `.`s. 156
* Explain why previous value is dropped from window. 157
* Handle window center before right side `for`-loop. 158

* Drop Python 3.4. 121
* Remove VIGRA support. 122
* Fix Cython rank type to `double`. 120
* Use conda-build compiler syntax in recipe. 124
* Use NumPy's `ndindex` instead of `itertools`. 123
* Make Cython import a `cimport`. 125
* Fix Cython `half_length` type to `size_t`. 126
* Use Python 3 division on Python 2. 127
* Make quotes consistent. 128
* Fix `half_length` name in `lineRankOrderFilter`. 130
* Simplify fused type wrapper `lambda`. 131
* Cleanup the `for`-loop a bit. 132
* Use NumPy's `copyto` to copy `image` to `out`. 133
* Check that `rank` is between `0.0` and `1.0`. 135
* Validate image. 136
* Drop check for non-negative `half_length`. 137
* Drop extra blank line. 138
* Remove lambda wrappers. 139
* Use ndarray type. 134
* Refactor reused loop variables. 141
* Use float pointers in Cython/C++ binding function. 142
* Fix-up some errors. 140
* Use pointers in `ndindex`. 143
* Refactor single and double precision `while`-loops. 144
* Fix-up some errors (pt. 2). 145
* Simplify looping code and drop unneeded code. 146
* Tidy up C++. 147
* Minor C++ optimizations. 148
* Rename `image` to `a`. 149
* Use size_t indices. 150
* Drop Windows 32-bit. 151

* Fixes some issues with newer conda-forge packages and simplifies CI. 115
* Require the VIGRA tests pass on Travis CI. 116
* More trove classifiers and conda-forge badge. 117

* Support Python 3.4 on Unix. 92
* Add NumPy 1.13 to the Travis CI test matrix. 93
* Require VIGRA 1.11.0+. 95
* Require Cython. 94
* Test Python 3.4 and NumPy 1.13. 96
* Drop old VIGRA Python bindings. 98
* Cleanup recipe. 99
* Fix comments. 100
* Use Boost's round. 101
* Use distance function to find iterator separation. 102
* Allow multithreaded Boost libraries. 103
* Standardize template types. 106
* Preallocate deque used for the filter window. 107
* Handle filter window reaching end of source. 108
* Simplify the wraparound mirroring index math. 109
* Support Windows. 97

* Group CI matrix by Python version. 91
* Fix linkage to vigranumpy on Mac. 89
* Detect Python library name. 88
* Tidy up Python inspection. 87
* Fix Mac build. 85
* Drop `.cpp` from our globbed sources. 84
* Update manifest. 83
* Add Python 3.6 to Travis CI's matrix. 82
* NumPy 1.11, 1.12 matrix. 77
* Rename directory `test` to `tests`. 81
* Drop cleanup step from `conda-build` recipe. 80
* CMake test cleanup. 79
* Fix recipe tests. 78
* Specify the Python version to build against on Travis. 76
* License 2017. 74
* Fix CI build. 75
* Import `setuptools` before `distutils`. 71