Add a little more test coverage (#1805)

Format main.cpp files more consistently

Add `make format` to run clang-format on everything

test/asm/empty-state.out

@@ -0,0 +1,16 @@
+; File generated by rgbasm
+
+; Numeric constants
+; No values
+
+; Variables
+; No values
+
+; String constants
+; No values
+
+; Character maps
+newcharmap main
+
+; Macros
+; No values