git-sugdiff: Use `diff_options.parse()` to extract diff options

Config::get():
Change `args` type so we can pass both a `Vec<String>` and
`Vec<&String>`.

diff_options.parse():
* Split diff arguments and program arguments by returning a tuple.
* Exit the args loop once we've parsed an argument.
* Update test
* Add a non-working test for suggestion arguments. An `OPT_OPTIONS`
  argument could be followed by an argument that's not the value of the
  `OPT_OPTIONS` option. Currently, that arg will always be parsed as the
  value. We need to handle this case.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/config.rs b/src/config.rs
index d8732d4..77793c4 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -15,6 +15,7 @@
 
 
 use std::env;
+use std::ffi::OsStr;
 use std::process;
 
 use getopts::{self, Options};
@@ -57,7 +58,9 @@ pub struct Config {
 impl Config {
     /// Set up command line arguments. Extract configuration values from command
     /// line arguments, Git config, and environment variables.
-    pub fn get(args: &[String], usage_brief: &str) -> Result<Self, Error> {
+    // pub fn get<C: IntoIterator>(args: C, usage_brief: &str) -> Result<Self, Error>
+    // where C::Item: AsRef<OsStr>
+    pub fn get<S: AsRef<OsStr>>(args: &[S], usage_brief: &str) -> Result<Self, Error> {
         let mut opts = Options::new();
 
         opts.optopt(