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).
