Opexebo

* Update dependencies for more modern versions (particularly `numpy`, `scipy` and `pytest`)
* Switch supported Python versions for 3.8+

* Fix some docstrings that were not updated to reflect changes in 0.6.0
* Fix the default limit behaviour of `accumulate_spatial` for bin width specification.

* Rewrite `spatial_occupancy` and `rate_map` to remove the walk filter (signature breaking)
* The individual analysis functions should be single purpose, and the walk-filter breaks this rule.
* Ideally, the walk-filter should be applied to spikes/tracking data _first_, and the resulting data then used for further analysis.
* A dedicated function has been provided to replace this: `general.walk_filter`
* Rewrite `shuffle` to better handle edge cases (including 1-spike-only) (signature breaking)
* Added `general.walk_filter` to provide replace the specific filtering implemented in each of `spatial_occupancy` and `rate_map`

* Fix a bug where `accumulate_spatial` can't handle cases where a single spike is present
* Fix an error in the LFP power spectrum calculation with fft
* Removed support for providing 1D position data as a 2d array with length 1
* Caused frustrating circular issues in cases where only a single data point was provided.
* Fairly low value addition, so support removed.

* Publish to PyPi

* Support 1D data in spatial occupancy and ratemap
* Add Opexebo-specific errors
* Add automated testing prior to release
* Add `calculate_speed`
* Add `egocentric_occupancy`
* Fixed an edge case error in `accumulate_spatial`

* Substantial cleanup to `accumulate_spatial`
- Function was mathematically correct but confusing, due to the difference between opexebo's standard of `(x, y)` and NumPy's standard of `(y, x)`
* Added `upsampling`
* Added `circular_mask`
* Mandatory keyword arguments have been made positional
* `peak_search` updated to handle issues with MaskedArrays containing negative values
* Dcumentation expanded, made Sphinx compatible, and published on ReadTheDocs
* Further work on BorderScore, still experimental though
- Functional for Rectangular arenas
- Circular arenas are still WIP, should not be relied upon yet.