Add NSString category for HTML related methods

Also remove macros scattered throughout the code and use category consistently

HTMLKit/HTMLCharacterToken.m

@@ -7,19 +7,7 @@
 //
 
 #import "HTMLCharacterToken.h"
-
-NS_INLINE BOOL isHtmlWhitespace(char c)
-{
-	return c == ' ' || c == '\t' || c == '\n' || c == '\f' || c == '\r';
-}
-
-NS_INLINE size_t LeadingWhitespaceLength(NSString *string)
-{
-	const char *str = string.UTF8String;
-	size_t idx = 0;
-	while (isHtmlWhitespace(*str)) { str++; idx++; }
-	return idx;
-}
+#import "NSString+HTMLKit.h"
 
 @interface HTMLCharacterToken ()
 {
@@ -48,14 +36,12 @@ NS_INLINE size_t LeadingWhitespaceLength(NSString *string)
 
 - (BOOL)isWhitespaceToken
 {
-#warning Cache Character Set
-	NSCharacterSet *set = [[NSCharacterSet characterSetWithCharactersInString:@" \t\n\f"] invertedSet];
-	return [_characters rangeOfCharacterFromSet:set].location == NSNotFound;
+	return [_characters isHTMLWhitespaceString];
 }
 
 - (HTMLCharacterToken *)tokenByRetainingLeadingWhitespace
 {
-	size_t index = LeadingWhitespaceLength(_characters);
+	NSUInteger index = _characters.leadingWhitespaceLength;
 	if (index > 0) {
 		NSString *leading = [_characters substringToIndex:index];
 		return [[HTMLCharacterToken alloc] initWithString:leading];
@@ -65,7 +51,7 @@ NS_INLINE size_t LeadingWhitespaceLength(NSString *string)
 
 - (HTMLCharacterToken *)tokenByTrimmingLeadingWhitespace
 {
-	size_t index = LeadingWhitespaceLength(_characters);
+	NSUInteger index = _characters.leadingWhitespaceLength;
 	if (index < _characters.length) {
 		NSString *remaining = [_characters substringFromIndex:index];
 		return [[HTMLCharacterToken alloc] initWithString:remaining];