More deriving (#885)

* Enhance SimpleSpan with additional traits

Added Default and PartialOrd, Ord traits to SimpleSpan.

* Add PartialOrd and Ord traits to Rich struct

Author: Lokathor

src/error.rs

@@ -602,7 +602,7 @@ where
 /// assert_eq!(error.found(), Some(&'5'));
 ///
 /// ```
-#[derive(Clone, PartialEq, Eq, Hash)]
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Rich<'a, T, S = SimpleSpan<usize>> {
     span: S,
     reason: Box<RichReason<'a, T>>,

src/span.rs

@@ -85,7 +85,7 @@ pub trait Span {
 /// The most basic implementor of `Span` - akin to `Range`, but `Copy` since it's not also
 /// an iterator. Also has a `Display` implementation
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct SimpleSpan<T = usize, C = ()> {
     /// The start offset of the span.
     pub start: T,