Vertically travelling redstone dust does not visually connect to adjacent lines of vertical redstone dust, despite being logically connected

Relates to MC-2255, MC-181512, MC-181524 and MC-181636

When a line of redstone dust is travelling up the side of a block, and is directly next to another line of redstone doing the same thing, the length of redstone which is travelling upwards will not actually visually connect to the adjacent lines, which makes no sense as the lines are indeed connected logically, as can be seen by powering them. Visually the result is several directly adjacent parallel lines of redstone, which is impossible to get on flat ground surfaces and is just nonsensical.

This could be fixed by introducing new block states for redstone - currently each compass direction can have the values none, side and up - this could be expanded so that each compass direction has six different possibilities, namely none, side, up, up_left, up_right and up_left_right. There could perhaps be a way to achieve this in even less states, but I'm not entirely sure.