Remove the global buffer and instead a context-specific one

Cargo.toml

@@ -19,6 +19,7 @@ name = "liner"
 bytecount = "0.3.1"
 termion = { git = "https://gitlab.redox-os.org/redox-os/termion" }
 unicode-width = "0.1.*"
+itertools = "*"
 
 [dev-dependencies]
 regex = "1.0.0"

src/context.rs

@@ -50,6 +50,7 @@ pub struct Context {
     pub history: History,
     pub word_divider_fn: Box<Fn(&Buffer) -> Vec<(usize, usize)>>,
     pub key_bindings: KeyBindings,
+    pub buf: String,
 }
 
 impl Context {
@@ -58,6 +59,7 @@ impl Context {
             history: History::new(),
             word_divider_fn: Box::new(get_buffer_words),
             key_bindings: KeyBindings::Emacs,
+            buf: String::with_capacity(512),
         }
     }
 

src/lib.rs

 extern crate bytecount;
+extern crate itertools;
 extern crate termion;
 extern crate unicode_width;