All: rename every function from UpperCamelCase to snake_case

This was a mess since I didn't know which to use but now I decided
to go with snake_case :)

kernel/include/kernel/Debug.h

@@ -28,6 +28,6 @@
 
 namespace Debug
 {
-	void DumpStackTrace();
+	void dump_stack_trace();
 	void putchar(char);
 }