strtoattr() now ignores Ctrl-A chars in the string... as attrstr() used to

This returns bug-compatibility with attrstr(), at least for Ctrl-A chars,
so that if someone is for example, assigning a Ctrl-A sequence to JS
console.attributes, that'll work (again) as it did in SBBS v3.19.

Any other invalid chars in the string will stop the parsing, still, even
though that's not how attrstr() worked.

For Kirkman's doorgame/script backward compatibility.

src/sbbs3/scfglib2.c

@@ -778,6 +778,7 @@ char *u32toaf(uint32_t l, char *str)
 
 /****************************************************************************/
 /* Returns the actual attribute code from a string of ATTR characters       */
+/* Ignores any Ctrl-A characters in the string (as attrstr() used to)       */
 /****************************************************************************/
 uint strtoattr(const char *str, char** endptr)
 {
@@ -787,6 +788,8 @@ uint strtoattr(const char *str, char** endptr)
 	atr = LIGHTGRAY;
 	while (str[l]) {
 		switch (toupper(str[l])) {
+			case CTRL_A:
+				break;
 			case 'H':   /* High intensity */
 				atr |= HIGH;
 				break;