Fix checking of backslash in link text (#510) (#512)

inline.go

@@ -252,7 +252,7 @@ func link(p *parser, out *bytes.Buffer, data []byte, offset int) int {
 		case data[i] == '\n':
 			textHasNl = true
 
-		case data[i-1] == '\\':
+		case isBackslashEscaped(data, i):
 			continue
 
 		case data[i] == '[':

testdata/Links, inline style.html

@@ -8,4 +8,6 @@
 
 <p><a href="/url/" title="title has spaces afterward">URL and title</a>.</p>
 
+<p><a href="/url/">URL with backslashes\</a>.</p>
+
 <p>[Empty]().</p>

testdata/Links, inline style.text

@@ -8,5 +8,6 @@ Just a [URL](/url/).
 
 [URL and title](/url/ "title has spaces afterward"  ).
 
+[URL with backslashes\\](/url/).
 
 [Empty]().