Graphite - Rulers

I have made the rulers functional for graphite, a work in progress vector editor written in the Rust programming language with Web Assembly. This was a smaller MR (merge request) with the main challenge being to dynamically adjust the distance between the major numbered lines so that the increments where round numbers. I achieved this through base 2 logarithms, a function which I had not previously come across. This allows the interval to double or half as many times as necessary for the current zoom, whilst maintaining a sensible gap of 51-100px between each number. I also had some issues with the modulus function not working correctly on negative numbers in javascript which took quite a bit of debugging to track down. This emphasized for me the value of planning things out on paper. The functionality is avaliable on the master branch build of graphite at editor.graphite.design/ The canvas can be moved with the middle mouse button, space plus left mouse button drag or with the scrollbars after drawing a shape.