Regualrize escape characters

Regularized the case statements in qio.c, str.c, and token.c
that relate to escape characters.

The '\a' is now recognized in a printf format string as the
single byte audible bell character (byte 0x07 in ASCII encoding).

The following is a partial list of escape sequences recognized
in strings and in printf formats:

    \a      audible bell    byte 0x07 in ASCII encoding
    \b      backspace       byte 0x08 in ASCII encoding
    \f      form feed       byte 0x0c in ASCII encoding
    \n      newline         byte 0x0b in ASCII encoding
    \r      return          byte 0x0a in ASCII encoding
    \t      tab             byte 0x0d in ASCII encoding
    \v      vertical tab    byte 0x09 in ASCII encoding

qio.c

@@ -62,12 +62,13 @@ qprintf(char *fmt, ...)
 			if (ch == '\\') {
 				ch = *fmt++;
 				switch (ch) {
+				case 'a': ch = '\a'; break;
+				case 'b': ch = '\b'; break;
+				case 'f': ch = '\f'; break;
 				case 'n': ch = '\n'; break;
 				case 'r': ch = '\r'; break;
 				case 't': ch = '\t'; break;
-				case 'f': ch = '\f'; break;
 				case 'v': ch = '\v'; break;
-				case 'b': ch = '\b'; break;
 				case 0:
 					va_end(ap);
 					return;

str.c

@@ -1380,17 +1380,17 @@ printechar(char *c)
 	math_chr('\\');
 	ech = 0;
 	switch (ch) {
+	case '\a': ech = 'a'; break;
+	case '\b': ech = 'b'; break;
+	case '\f': ech = 'f'; break;
 	case '\n': ech = 'n'; break;
 	case '\r': ech = 'r'; break;
 	case '\t': ech = 't'; break;
-	case '\b': ech = 'b'; break;
-	case '\f': ech = 'f'; break;
 	case '\v': ech = 'v'; break;
 	case '\\': ech = '\\'; break;
 	case '\"': ech = '\"'; break;
 	case '\'': ech = '\''; break;
 	case 0: ech = '0'; break;
-	case 7: ech = 'a'; break;
 	case 27: ech = 'e'; break;
 	}
 	if (ech == '0') {
@@ -1438,8 +1438,17 @@ fitstring(char *str, long len, long width)
 			continue;
 		n++;
 		switch (ch) {
-		case '\n': case '\r': case '\t': case '\b': case '\f':
+		case '\a':
-		case '\v': case '\\': case '\"': case 7: case 27:
+		case '\b':
+		case '\f':
+		case '\n':
+		case '\r':
+		case '\t':
+		case '\v':
+		case '\\':
+		case '\"':
+		case '\'':
+		case 27:
 			continue;
 		}
 		if (ch >= 64 || (nch >= '0' && nch <= '7')) {

token.c

@@ -183,10 +183,12 @@ gettoken(void)
 		}
 		switch (ch) {
 		case ' ':
-		case '\t':
+		case '\a':
-		case '\r':
+		case '\b':
-		case '\v':
 		case '\f':
+		case '\r':
+		case '\t':
+		case '\v':
 		case '\0':
 			break;
 		case '\n':