Fix the scale lines looking uneven

Some lines were being drawn at non-integral positions.
The x and y coordinates are now floored before use.

macrovision.js

@@ -772,6 +772,9 @@ function drawVerticalScale(ifDirty = false) {
         const oldStroke = ctx.strokeStyle;
         const oldFill = ctx.fillStyle;
 
+        x = Math.round(x);
+        y = Math.round(y);
+
         ctx.beginPath();
         ctx.moveTo(x, y);
         ctx.lineTo(x + 20, y);
@@ -969,6 +972,9 @@ function drawHorizontalScale(ifDirty = false) {
     function drawTick(/** @type {CanvasRenderingContext2D} */ ctx, x, y, label) {
         ctx.save()
 
+        x = Math.round(x);
+        y = Math.round(y);
+
         ctx.beginPath();
         ctx.moveTo(x, y);
         ctx.lineTo(x, y + 20);