ui: Force LTR direction on the nodes port grid and on ports
Forces the direction on the nodes internal port grid and on the ports themselves to be always left-to-right (LTR), to avoid the UI becoming messed up when defaulting to right-to-left (RTL).
Previously, when using RTL, the side of input and output ports would be swapped, causing the port handles to be inside the node instead of at the edge.
Fixes #117 (closed)