Move InputFile to separate module

src/app.rs

@@ -15,6 +15,7 @@ use ansi_term;
 
 use assets::BAT_THEME_DEFAULT;
 use errors::*;
+use inputfile::InputFile;
 use line_range::LineRange;
 use style::{OutputComponent, OutputComponents, OutputWrap};
 
@@ -25,13 +26,6 @@ pub enum PagingMode {
     Never,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq)]
-pub enum InputFile<'a> {
-    StdIn,
-    Ordinary(&'a str),
-    ThemePreviewFile,
-}
-
 #[derive(Clone)]
 pub struct Config<'a> {
     /// List of files to print