SciPy 1-D filters

_From @jakirkham on May 2, 2017 23:56_

The list of functions below are a set of 1-D filters. These all come from SciPy. In particular they come from [`scipy.ndimage.filters`]( https://docs.scipy.org/doc/scipy-0.19.0/reference/ndimage.html#filters ). They are not a near term priority. They may be included in this library or potentially another wrapper library.

* [ ] [convolve1d]( https://docs.scipy.org/doc/scipy-0.19.0/reference/generated/scipy.ndimage.convolve1d.html )
* [ ] [correlate1d]( https://docs.scipy.org/doc/scipy-0.19.0/reference/generated/scipy.ndimage.correlate1d.html )
* [ ] [gaussian_filter1d]( https://docs.scipy.org/doc/scipy-0.19.0/reference/generated/scipy.ndimage.gaussian_filter1d.html )
* [ ] [generic_filter1d]( https://docs.scipy.org/doc/scipy-0.19.0/reference/generated/scipy.ndimage.generic_filter1d.html )
* [ ] [maximum_filter1d]( https://docs.scipy.org/doc/scipy-0.19.0/reference/generated/scipy.ndimage.maximum_filter1d.html )
* [ ] [minimum_filter1d]( https://docs.scipy.org/doc/scipy-0.19.0/reference/generated/scipy.ndimage.minimum_filter1d.html )
* [ ] [uniform_filter1d]( https://docs.scipy.org/doc/scipy-0.19.0/reference/generated/scipy.ndimage.uniform_filter1d.html )

_Copied from original issue: dask-image/dask-ndfilters#14_