Adding stub file of cm.py

[beskep]

Is your feature request related to a problem? Please describe.

Adding stub file of cm.py would be very helpful for auto completing and type checking.

Describe the solution you would like

cm.pyi would be like the following:

from matplotlib.colors import ListedColormap as LC

CMAP_DCT = dict[str, LC]
cmap_d: CMAP_DCT
cmap_cd: dict[str, CMAP_DCT]

amber: LC
amber_r: LC
amethyst: LC
amethyst_r: LC
apple: LC
apple_r: LC
arctic: LC
arctic_r: LC
⋮

I generated the stub file with this script:

from pathlib import Path

import cmasher.cm as cmrcm
from cmasher._known_cmap_types import _CMASHER_BUILTIN_MAP_TYPES

if __name__ == "__main__":
    pyi = Path(cmrcm.__file__).with_suffix(".pyi")

    with pyi.open("w", encoding="utf-8") as f:
        f.write(
            """from matplotlib.colors import ListedColormap as LC

CMAP_DCT = dict[str, LC]
cmap_d: CMAP_DCT
cmap_cd: dict[str, CMAP_DCT]

"""
        )

        for cmap in _CMASHER_BUILTIN_MAP_TYPES:
            if cmap.startswith("cmr."):
                continue

            f.write(f"{cmap}: LC\n")
            f.write(f"{cmap}_r: LC\n")

Additional context

[neutrinoceros]

This would be a useful addition indeed, PR welcome !
The script used for generation would need to be added to scripts too.

[beskep]

#111 Thank you for kind response. This is my first PR :)

[neutrinoceros]

closed in #112 , thanks again !