Store line endings on a per-line basis in Buffer

The line ending for each line is recorded and reused
when lines are modified or inserted.

Closes #166

src/app/editor.coffee

@@ -1076,8 +1076,11 @@ class Editor extends View
         position += token.value.length
 
     popScope() while scopeStack.length > 0
-    if not @mini and invisibles?.eol
-      line.push("<span class='invisible'>#{invisibles.eol}</span>")
+    if invisibles and not @mini
+      if invisibles.cr and screenLine.lineEnding is '\r\n'
+        line.push("<span class='invisible'>#{invisibles.cr}</span>")
+      if invisibles.eol
+        line.push("<span class='invisible'>#{invisibles.eol}</span>")
 
     line.push('</pre>')
     line.join('')