Ponder: Replace Doubles with Floats where possible

[migueldeicaza]

The API sometimes surfaces doubles, when it is not necessary.

We still use the double API for interop, but would be useful to not confuse people:

https://github.com/godotengine/godot-cpp/pull/1433/files

[elijah-semyonov]

Referenced PR superseded by godotengine/godot-cpp#1555