Features:
* Python 3 compatible
* Now standalone `gridspeccer` binary
* Add option `--output-folder`
* Add `make_spines_{all,right}()` helper functions
Formatting:
* `README` reworked
* Ongoing effort to transform an organic sets of scripts created with a looming deadline into a usable tool
* Ran `black` to reduce linter errors -> still work left to be done
Fixes:
* Converted to Python 3
* Do not mask errors when calling `adjust_axes()`
* Ensured all helper functions are exposed.