FIX: preventing signed/unsigned mismatch warnings in Visual Studio

Author: Oldes

src/core/d-dump.c

@@ -70,7 +70,7 @@
 	REBCNT cnt = 0;
 
 	cp = buf;
-	for (l = 0; l < max_lines; l++) {
+	for (l = 0; (int)l < max_lines; l++) {
 		cp = Form_Hex_Pad(cp, (REBUPT) bp, 8);
 
 		*cp++ = ':';

src/core/n-loop.c

@@ -202,7 +202,7 @@
 	bodi = VAL_INDEX(D_ARG(mode+2));
 
 	// Starting location when past end with negative skip:
-	if (inc < 0 && VAL_INDEX(var) >= (REBINT)VAL_TAIL(var)) {
+	if (inc < 0 && VAL_INDEX(var) >= VAL_TAIL(var)) {
 		VAL_INDEX(var) = (REBINT)VAL_TAIL(var) + inc;
 	}
 

src/core/s-unicode.c

@@ -783,7 +783,7 @@ ConversionResult ConvertUTF8toUTF32 (
 
 	// Check that we have enough valid source bytes:
 	if (len) {
-		if (slen+1 > *len) return 0;
+		if ((REBCNT)slen+1 > *len) return 0;
 	}
 	else {
 		for (; slen >= 0; slen--)

src/core/t-date.c

@@ -437,7 +437,7 @@
 
 	if (month < 1 || month > 12) return FALSE;
 
-	if (year > MAX_YEAR || day < 1 || day > (REBINT)(Month_Lengths[month-1])) return FALSE;
+	if (year > MAX_YEAR || day < 1 || day > (REBCNT)(Month_Lengths[month-1])) return FALSE;
 
 	// Check February for leap year or century:
 	if (month == 2 && day == 29) {