Extend RGBASM and RGBLINK verbosity flags to have multiple levels like RGBGFX (#1772)

include/verbosity.hpp

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: MIT
+
+#ifndef RGBDS_VERBOSITY_HPP
+#define RGBDS_VERBOSITY_HPP
+
+// This macro does not evaluate its arguments unless the condition is true.
+#define verbosePrint(level, ...) \
+	do { \
+		if (checkVerbosity(level)) { \
+			fprintf(stderr, __VA_ARGS__); \
+		} \
+	} while (0)
+
+enum Verbosity {
+	VERB_NONE,   // 0. Default, no extra output
+	VERB_CONFIG, // 1. Basic configuration, after parsing CLI options
+	VERB_NOTICE, // 2. Before significant actions
+	VERB_INFO,   // 3. Some intermediate action results
+	VERB_DEBUG,  // 4. Internals useful for debugging
+	VERB_TRACE,  // 5. Step-by-step algorithm details
+	VERB_VVVVVV, // 6. What, can't I have a little fun?
+};
+
+void incrementVerbosity();
+bool checkVerbosity(Verbosity level);
+
+void printVVVVVVerbosity();
+
+#endif // RGBDS_VERBOSITY_HPP