ADD: colorutils to handle hashed colors consistently across frontend

frontend/src/util/colorutil.js

+// https://gist.github.com/0x263b/2bdd90886c2036a1ad5bcf06d6e6fb37
+// (modified)
+String.prototype.toHSL = function(opts) {
+    let h, s, l;
+    opts = opts || {};
+    opts.hue = opts.hue || [0, 360];
+    opts.sat = opts.sat || [75, 100];
+    opts.lit = opts.lit || [40, 60];
+
+    let range = function(hash, min, max) {
+        let diff = max - min;
+        let x = ((hash % diff) + diff) % diff;
+        return x + min;
+    }
+
+    let hash = 0;
+    if (this.length === 0) return hash;
+    for (let i = 0; i < this.length; i++) {
+        hash = this.charCodeAt(i) + ((hash << 5) - hash);
+        hash = hash & hash;
+    }
+
+    h = range(hash, opts.hue[0], opts.hue[1]);
+    s = range(hash, opts.sat[0], opts.sat[1]);
+    l = range(hash, opts.lit[0], opts.lit[1]);
+
+    return `hsl(${h}, ${s}%, ${l}%)`;
+}
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