Started adding validation layer.

src/log.h

@@ -0,0 +1,16 @@
+#ifndef VKE_LOG_H
+#define VKE_LOG_H
+
+#define VKE_LOG_DEBUG = 0
+#define VKE_LOG_ERROR = 1
+
+// Sets the global log level (VKE_LOG_DEBUG by default).
+void vkeSetLogLevel(int level);
+
+// Logs the given message with the DEBUG tag.
+void vkeLogDebug(const char* message);
+
+// Logs the given message with the ERROR tag.
+void vkeLogError(const char* message);
+
+#endif