Remove code that tries to handle ANSI escape inputs (#2189)

Syntax highlighting is broken when input contains ANSI escape characters
anyway, so there is not much point in trying to handle ANSI escapes in
input.

src/preprocessor.rs

@@ -1,35 +1,26 @@
-use console::AnsiCodeIterator;
-
 /// Expand tabs like an ANSI-enabled expand(1).
-pub fn expand_tabs(line: &str, width: usize, cursor: &mut usize) -> String {
-    let mut buffer = String::with_capacity(line.len() * 2);
+pub fn expand_tabs(mut text: &str, width: usize, cursor: &mut usize) -> String {
+    let mut buffer = String::with_capacity(text.len() * 2);
 
-    for chunk in AnsiCodeIterator::new(line) {
-        match chunk {
-            (text, true) => buffer.push_str(text),
-            (mut text, false) => {
-                while let Some(index) = text.find('\t') {
-                    // Add previous text.
-                    if index > 0 {
-                        *cursor += index;
-                        buffer.push_str(&text[0..index]);
-                    }
-
-                    // Add tab.
-                    let spaces = width - (*cursor % width);
-                    *cursor += spaces;
-                    buffer.push_str(&*" ".repeat(spaces));
-
-                    // Next.
-                    text = &text[index + 1..text.len()];
-                }
-
-                *cursor += text.len();
-                buffer.push_str(text);
-            }
+    while let Some(index) = text.find('\t') {
+        // Add previous text.
+        if index > 0 {
+            *cursor += index;
+            buffer.push_str(&text[0..index]);
         }
+
+        // Add tab.
+        let spaces = width - (*cursor % width);
+        *cursor += spaces;
+        buffer.push_str(&*" ".repeat(spaces));
+
+        // Next.
+        text = &text[index + 1..text.len()];
     }
 
+    *cursor += text.len();
+    buffer.push_str(text);
+
     buffer
 }