Move objects to a lower exit class.

Paragraph's exit matcher which detects elements was causing the plain list parser to exit after the first item was parsed which was causing significant amounts of re-parsing.

src/parser/plain_link.rs

@@ -113,7 +113,7 @@ fn path_plain<'r, 's>(
     // TODO: "optionally containing parenthesis-wrapped non-whitespace non-bracket substrings up to a depth of two. The string must end with either a non-punctation non-whitespace character, a forwards slash, or a parenthesis-wrapped substring"
     let parser_context =
         context.with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
-            class: ExitClass::Beta,
+            class: ExitClass::Gamma,
             exit_matcher: &path_plain_end,
         }));