Adopt field init shorthand in a few places

Found by running 'egrep "(\b[a-zA-Z]+): \1\b" -R src'

src/commands/command.rs

@@ -168,7 +168,7 @@ impl CommandArgs {
         Ok(RunnableArgs {
             args: T::deserialize(&mut deserializer)?,
             context: RunnableContext {
-                input: input,
+                input,
                 commands: registry.clone(),
                 shell_manager,
                 name: name_span,
@@ -201,7 +201,7 @@ impl CommandArgs {
         Ok(RunnableRawArgs {
             args: T::deserialize(&mut deserializer)?,
             context: RunnableContext {
-                input: input,
+                input,
                 commands: registry.clone(),
                 shell_manager,
                 name: name_span,

src/commands/enter.rs

@@ -109,7 +109,7 @@ impl PerItemCommand for Enter {
                                                 })) => {
                                                     yield Ok(ReturnSuccess::Action(CommandAction::EnterValueShell(
                                                         Tagged {
-                                                            item: item,
+                                                            item,
                                                             tag: contents_tag,
                                                         })));
                                                 }

src/commands/open.rs

@@ -113,7 +113,7 @@ fn run(
                             }
                         }
                         Ok(ReturnSuccess::Value(Tagged { item, .. })) => {
-                            yield Ok(ReturnSuccess::Value(Tagged { item: item, tag: contents_tag }));
+                            yield Ok(ReturnSuccess::Value(Tagged { item, tag: contents_tag }));
                         }
                         x => yield x,
                     }

src/commands/post.rs

@@ -123,7 +123,7 @@ fn run(
                             }
                         }
                         Ok(ReturnSuccess::Value(Tagged { item, .. })) => {
-                            yield Ok(ReturnSuccess::Value(Tagged { item: item, tag: contents_tag }));
+                            yield Ok(ReturnSuccess::Value(Tagged { item, tag: contents_tag }));
                         }
                         x => yield x,
                     }

src/commands/save.rs

@@ -101,8 +101,8 @@ fn save(
                 let command_name = format!("to-{}", extension.to_str().unwrap());
                 if let Some(converter) = registry.get_command(&command_name) {
                     let new_args = RawCommandArgs {
-                        host: host,
-                        shell_manager: shell_manager,
+                        host,
+                        shell_manager,
                         call_info: UnevaluatedCallInfo {
                             args: crate::parser::hir::Call {
                                 head: raw_args.call_info.args.head,

src/errors.rs

@@ -140,7 +140,7 @@ impl ShellError {
         ProximateShellError::ArgumentError {
             command: command.into(),
             error: kind,
-            span: span,
+            span,
         }
         .start()
     }

src/parser/deserializer.rs

@@ -278,8 +278,8 @@ struct StructDeserializer<'a, 'de: 'a> {
 impl<'a, 'de: 'a> StructDeserializer<'a, 'de> {
     fn new(de: &'a mut ConfigDeserializer<'de>, fields: &'static [&'static str]) -> Self {
         StructDeserializer {
-            de: de,
-            fields: fields,
+            de,
+            fields,
         }
     }
 }