Reorganize GDScript codebase

[rmgaray]

Fix #19 .

Depends on #8 .

• [x] Split demo from SDK / library
• [x] Rename script files according to style guide
• ~[ ] Update .gitignore and .gitattributes for asset store distribution~ We need to work this more.
• [x] Fix Nix build

[rmgaray]

Thanks @brainrake for the fix, that did it. I will open for review (once I update the git attributes).

EDIT: On second thought, the gitattributes approach will not work because the libcsl_godot library is still needed. We will have to do that on a separate PR.

[brainrake]

I think we need to add a nix package that builds the Asset. We can then add it a release artifact. I checked the submission guide and form, and we can choose a custom hosting method (instead of GitHub) and enter a download URL instead of a commit. We can of course also push a commit and use GitHub method, but that seems more involved.

[rmgaray]

I think we need to add a nix package that builds the Asset. We can then add it a release artifact. I checked the submission guide and form, and we can choose a custom hosting method (instead of GitHub) and enter a download URL instead of a commit. We can of course also push a commit and use GitHub method, but that seems more involved.

As we discussed in the one of our weeklies, we can work on the nix package for building the asset at a later stage and in a separate PR. Thanks for the comments.

[brainrake]

related: #24