Add Hashable support for CG types (#6)

Author: Kyle-Ye

Sources/OpenCoreGraphics/CGGeometry+Hashable.swift

@@ -0,0 +1,28 @@
+//
+//  CGGeometry+Hashable.swift
+//  OpenCoreGraphics
+
+#if !canImport(Darwin)
+// Foundation does not provide Hashable conformance for CG types yet.
+// See https://github.com/swiftlang/swift-corelibs-foundation/issues/5275
+extension CGPoint: Hashable {
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(x)
+        hasher.combine(y)
+    }
+}
+
+extension CGSize: Hashable {
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(width)
+        hasher.combine(height)
+    }
+}
+
+extension CGRect: Hashable {
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(origin)
+        hasher.combine(size)
+    }
+}
+#endif