Cspyce

Cosmetic changes to README.md.

Support Python 3.12.
Complete testing of all scalar functions.
Significant internal cleanup including fixing memory leaks.
Fix bugs with `dskgd`, `dskmi2`, `dskv02`, `ekacld`, `ekgd`, `ekifld`,
`ekrcei`, `ekssum`, `frmchg`, `gcpool`, `gfocce`, `gfvent`, `lparse`, `lparsm`,
`matchi`, `matchw`, `prompt`, `refchg` and many others.
Allow all functions that expect a filename/path argument to accept a string,
byte string, or `pathlib.Path` object.
Implement SpiceCell data type.
Implement Plane and Ellipse data types.
Add IDE-detectable docstrings to all functions.
For full details see the top-level `README.md` and the docstrings for each
function.

Fix various memory corruption issues that caused crashing under MacOS.
Fix implementation issues with `dafgda`, `dafus`, `dasrdc`, `dp2hx`,
and `dskd02`.

Stable release using new release process. Remove all Python 2 support.
Add `cspyce.__version__` attribute. Fix bug with converting longlong to float
on Windows. Fix bug in `ckfxfm` where it was calling the wrong underlying
CSPICE function.

Convert LICENSE.txt to LICENSE.md. Improvements to release process and
documentation. Fix bug in `ckw01` and failing typemap tests.

Fix minor bug in aliases, fix lmpool, fix problems with array support.
Add LICENSE.txt.