Number input sliders should have typeable number input/output

[hudson-newey]

Users have expressed that using the slider to get a specific number (e.g. a specific grid size value) can be frustrating.

Having a typeable input that has up/down arrows (a HTML <input type="number" />) next to the slider input should fix this issue.

[hudson-newey]

To make the slider more usable, we should also add tick marks important intervals