Redo the superscript and relaxed emphasis flags into

NOSUPERSCRIPT and NORELAXED, so the default is to have them
turned on and you need to turn them off (or do STRICT) explicitly.

main.c

@@ -58,6 +58,8 @@ static struct {
     { "safelink",0, MKD_SAFELINK },
     { "del",     1, MKD_NOSTRIKETHROUGH },
     { "strikethrough", 1, MKD_NOSTRIKETHROUGH },
+    { "superscript", 1, MKD_NOSUPERSCRIPT },
+    { "emphasis",    0, MKD_NORELAXED },
     { "1.0",     0, MKD_1_COMPAT },
 } ;