layout: rethonk layouts from the ground up (#12890)

Rewrites layouts to be much smaller, and deal with much less annoying
BS. Improves the overall architecture, unifies handling of pseudotiling,
and various other improvements.

src/layout/algorithm/TiledAlgorithm.hpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "../../helpers/math/Math.hpp"
+#include "../../helpers/memory/Memory.hpp"
+
+#include "ModeAlgorithm.hpp"
+
+namespace Layout {
+
+    class ITarget;
+    class CAlgorithm;
+
+    class ITiledAlgorithm : public IModeAlgorithm {
+      public:
+        virtual ~ITiledAlgorithm() = default;
+
+        virtual SP<ITarget> getNextCandidate(SP<ITarget> old) = 0;
+
+      protected:
+        ITiledAlgorithm() = default;
+
+        WP<CAlgorithm> m_parent;
+
+        friend class Layout::CAlgorithm;
+    };
+}