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/citation.rs

@@ -90,7 +90,7 @@ fn global_prefix<'r, 's>(
             depth: 0,
         }))
         .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
-            class: ExitClass::Beta,
+            class: ExitClass::Gamma,
             exit_matcher: &global_prefix_end,
         }));
     let (remaining, (children, _exit_contents)) = verify(
@@ -151,7 +151,7 @@ fn global_suffix<'r, 's>(
             depth: 0,
         }))
         .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
-            class: ExitClass::Beta,
+            class: ExitClass::Gamma,
             exit_matcher: &global_suffix_end,
         }));
     let (remaining, (children, _exit_contents)) = verify(