Fix explicit line break parsing

It's possible for the input to end right after the explicit line break,
i.e. after the second \. This currently leads to an out of range index into
input (as the for loop starts with start+2 and [start:start+1] is the \\).

org/inline.go

@@ -129,7 +129,7 @@ func (d *Document) parseLineBreak(input string, start int) (int, Node) {
 }
 
 func (d *Document) parseExplicitLineBreak(input string, start int) (int, Node) {
-	if start == 0 || input[start-1] == '\n' || start+1 >= len(input) || input[start+1] != '\\' {
+	if start == 0 || input[start-1] == '\n' || start+2 >= len(input) || input[start+1] != '\\' {
 		return 0, nil
 	}
 	for i := start + 2; unicode.IsSpace(rune(input[i])); i++ {

org/testdata/inline.html

@@ -2,7 +2,8 @@
 <li>
 <p>
 <em>emphasis</em> and a hard line break <br>
-see?
+see? <br>
+also hard line breaks not followed by a newline get ignored, see \\
 </p>
 </li>
 <li>

org/testdata/inline.org

@@ -1,5 +1,6 @@
 - /emphasis/ and a hard line break \\
-  see?
+  see? \\
+  also hard line breaks not followed by a newline get ignored, see \\
 - /.emphasis with dot border chars./
 - /emphasis with a slash/inside/
 - /emphasis/ followed by raw text with slash /

org/testdata/inline.pretty_org

@@ -1,5 +1,6 @@
 - /emphasis/ and a hard line break \\
-  see?
+  see? \\
+  also hard line breaks not followed by a newline get ignored, see \\
 - /.emphasis with dot border chars./
 - /emphasis with a slash/inside/
 - /emphasis/ followed by raw text with slash /