Remove unnecessary context from some util functions.

src/parser/clock.rs

@@ -24,7 +24,7 @@ pub fn clock<'r, 's>(
     context: Context<'r, 's>,
     input: OrgSource<'s>,
 ) -> Res<OrgSource<'s>, Clock<'s>> {
-    start_of_line(context, input)?;
+    start_of_line(input)?;
     let (remaining, _leading_whitespace) = space0(input)?;
     let (remaining, _clock) = tag_no_case("clock:")(remaining)?;
     let (remaining, _gap_whitespace) = space1(remaining)?;