printer: add hyperlinks

This commit represents the initial work to get hyperlinks working and
was submitted as part of PR #2483. Subsequent commits largely retain the
functionality and structure of the hyperlink support added here, but
rejigger some things around.

crates/printer/src/lib.rs

@@ -67,6 +67,10 @@ fn example() -> Result<(), Box<Error>> {
 pub use crate::color::{
     default_color_specs, ColorError, ColorSpecs, UserColorSpec,
 };
+pub use crate::hyperlink::{
+    HyperlinkPath, HyperlinkPattern, HyperlinkPatternError, HyperlinkSpan,
+    HyperlinkValues,
+};
 #[cfg(feature = "serde1")]
 pub use crate::json::{JSONBuilder, JSONSink, JSON};
 pub use crate::standard::{Standard, StandardBuilder, StandardSink};
@@ -90,6 +94,8 @@ mod macros;
 
 mod color;
 mod counter;
+mod hyperlink;
+mod hyperlink_aliases;
 #[cfg(feature = "serde1")]
 mod json;
 #[cfg(feature = "serde1")]