This is consistent with the core Godot source code, and ensures the
license isn't detached from its original code when individual files
are distributed.
This is taken from the Godot repository, so formatting is similar. This
updates the style rules as well.
Also fix style in files to conform with this version.
The [] operator of Basis was returning a reference to a temporary, so fixed it.
There was no * operator in Transform equivalent to the xform function, which is
not in line with GDScript behavior.
Also fixed remaining cases where Transform relied on the old behavior of the
[] operator of Basis (i.e. that it returns the row, not the column).
Hugo Locurcio
George Marques
Marc Gilleron
Daniel Rakos
Bastiaan Olij
Karroffel