Prevent selection of bits while using drag functionality

[ahs3n]

When dragging across the bits to switch several of them at once, they would get selected as text. This behaviour was quite annoying so I added user-select: none to the input class. However, this also causes the labels above the bits to be unselectable, though I decided that's probably useful too in most cases. I think 90% of people won't mind not being able to copy a two digit number.