Significantly overhaul OPT code

Simplify the mess that was option setting (2 redundant variables !?)
Move options to a separate file
Have "modules" own their options, and OPT only access them (less redundancy)
Simplify code, respect naming conventions better

src/asm/parser.y

@@ -24,6 +24,7 @@
 #include "asm/macro.h"
 #include "asm/main.h"
 #include "asm/mymath.h"
+#include "asm/opt.h"
 #include "asm/output.h"
 #include "asm/rpn.h"
 #include "asm/section.h"