switch from open to opener

By default, `opener` launches the subprocess without waiting for its
completion, compared to `open` which waits for its completion.

This is helpful in case the `watch` feature is enabled and one of the
following commands `watch | serve --open` is used. If this command would
open the browser, listening for changes would be blocked by the browser.

Author: johannst

Cargo.lock

@@ -24,7 +24,7 @@ handlebars = "4.0"
 lazy_static = "1.0"
 log = "0.4"
 memchr = "2.0"
-open = "2.0"
+opener = "0.5"
 pulldown-cmark = "0.7.0"
 regex = "1.0.0"
 serde = "1.0"

Cargo.toml

@@ -133,7 +133,7 @@ fn get_book_dir(args: &ArgMatches) -> PathBuf {
 
 fn open<P: AsRef<OsStr>>(path: P) {
     info!("Opening web browser");
-    if let Err(e) = open::that(path) {
+    if let Err(e) = opener::open(path) {
         error!("Error opening web browser: {}", e);
     }
 }