Add compiledb, help and custom.py support

.gitignore

@@ -6,6 +6,12 @@ demo/bin/*
 !demo/bin/*.gdextension
 .sconsign*.dblite
 
+# Ignore custom.py
+custom.py
+
+# Ignore generated compile_commands.json
+compile_commands.json
+
 # Binaries
 *.o
 *.os