Improve history handling with regards to position and duplicates

src/lineengine/history.rs

@@ -3,7 +3,7 @@ use std::collections::VecDeque;
 pub struct History {
     pub entries: VecDeque<String>,
     pub max_size: usize,
-    current_position: Option<usize>,
+    pub current_position: Option<usize>,
 }
 impl Default for History {
     fn default() -> Self {

src/lineengine/line.rs

@@ -359,7 +359,11 @@ impl LineState {
                     self.clear_and_render(term)?;
 
                     // Add to history...
+                    if self.history.entries.front() != Some(&line) {
                         self.history.entries.push_front(line.clone());
+                        self.history.entries.truncate(self.history.max_size);
+                    }
+                    self.history.current_position = None;
 
                     // Return line
                     return Ok(Some(ReadlineEvent::Line(line)));