ALL: Avoid using is* macros from ctype.h

On some systems, passing signed chars to macros like isspace() etc. lead
to a runtime error. Hence, mark these macros as forbidden by default,
and introduce otherwise equivalent alternatives for them.

base/commandLine.cpp

@@ -277,7 +277,7 @@ void registerDefaults() {
 // resp. between "--some-option" and "--no-some-option".
 #define DO_OPTION_BOOL(shortCmd, longCmd) \
 	if (isLongCmd ? (!strcmp(s+2, longCmd) || !strcmp(s+2, "no-"longCmd)) : (tolower(s[1]) == shortCmd)) { \
-		bool boolValue = (islower(static_cast<unsigned char>(s[1])) != 0); \
+		bool boolValue = (isLower(s[1]) != 0); \
 		s += 2; \
 		if (isLongCmd) { \
 			boolValue = !strcmp(s, longCmd); \