remark-parse: fix support for image-like footnotes

Previously, image-like footnotes (such as `Hello![^foo]`) were seen
as image references if `footnotes: true` was passed.  However, it
makes much more sense, as pointed out in GH-283, that they are
footnotes instead.  This commit makes that happen.

Closes GH-283.

packages/remark-parse/lib/tokenize/reference.js

@@ -52,11 +52,13 @@ function reference(eat, value, silent) {
   queue = '';
 
   /* Check whether we’re eating a footnote. */
-  if (
-    self.options.footnotes &&
-    type === T_LINK &&
-    value.charAt(index) === C_CARET
-  ) {
+  if (self.options.footnotes && value.charAt(index) === C_CARET) {
+    /* Exit if `![^` is found, so the `!` will be seen as text after this,
+     * and we’ll enter this function again when `[^` is found. */
+    if (type === T_IMAGE) {
+      return;
+    }
+
     intro += C_CARET;
     index++;
     type = T_FOOTNOTE;

test/fixtures/input/footnote-without-space.text

@@ -1,5 +1,14 @@
 foo[^abc] bar. foo[^xyz] bar
 
+And some more tests for “image like” footnotes, related to:
+<https://github.com/remarkjs/remark/issues/283>:
+
+Hello[^footnote]
+Hello![^footnote]
+Hello! [^footnote]
+
 [^abc]: Baz baz
 
 [^xyz]: Baz
+
+[^footnote]: Some definition.