Merge branch 'side-effect-check' into 'master'

Stricter side effect checking

See merge request !5

src/kyut/side_effect.hpp

+#ifndef INCLUDE_kyut_side_effect_hpp
+#define INCLUDE_kyut_side_effect_hpp
+
+#include <cstdint>
+
+namespace kyut {
+    enum class SideEffect : std::int32_t {
+        none = 0,
+        read = 1,
+        write = 2,
+    };
+} // namespace kyut
+
+#endif // INCLUDE_kyut_side_effect_hpp