[orx-hash-grid] Add documentation, demos and improve API

orx-hash-grid/src/jvmDemo/kotlin/DemoHashGrid01.kt

@@ -0,0 +1,28 @@
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+import org.openrndr.extra.hashgrid.HashGrid
+import org.openrndr.extra.noise.uniform
+import kotlin.random.Random
+
+fun main() {
+    application {
+        configure {
+            width = 720
+            height = 720
+        }
+        program {
+            val r = Random(0)
+            val hashGrid = HashGrid(20.0)
+            extend {
+                val p = drawer.bounds.uniform(random = r)
+                if (hashGrid.isFree(p)) {
+                    hashGrid.insert(p)
+                }
+                drawer.circles(hashGrid.points().map { it.first }.toList(), 4.0)
+                drawer.fill = null
+                drawer.stroke = ColorRGBa.WHITE
+                drawer.rectangles(hashGrid.cells().map { it.bounds }.toList())
+            }
+        }
+    }
+}