Fix phantom lines in some CRLF files.

Fixes #415.  The issue was that cursor highlighting wasn't extending
to encompass the entire CRLF grapheme, and therefore ended up splitting
it.  This presumably was messing up other grapheme rendering as
well, and this fixes that as well.

helix-term/src/ui/editor.rs

@@ -8,7 +8,7 @@ use crate::{
 
 use helix_core::{
     coords_at_pos,
-    graphemes::ensure_grapheme_boundary,
+    graphemes::{ensure_grapheme_boundary, next_grapheme_boundary},
     syntax::{self, HighlightEvent},
     LineEnding, Position, Range,
 };
@@ -187,19 +187,24 @@ impl EditorView {
                     (cursor_scope, selection_scope)
                 };
 
+                let cursor_end = next_grapheme_boundary(text, range.head); // Used in every case below.
+
                 if range.head == range.anchor {
-                    spans.push((cursor_scope, range.head..range.head + 1));
+                    spans.push((cursor_scope, range.head..cursor_end));
                     continue;
                 }
 
                 let reverse = range.head < range.anchor;
 
                 if reverse {
-                    spans.push((cursor_scope, range.head..range.head + 1));
-                    spans.push((selection_scope, range.head + 1..range.anchor + 1));
+                    spans.push((cursor_scope, range.head..cursor_end));
+                    spans.push((
+                        selection_scope,
+                        cursor_end..next_grapheme_boundary(text, range.anchor),
+                    ));
                 } else {
                     spans.push((selection_scope, range.anchor..range.head));
-                    spans.push((cursor_scope, range.head..range.head + 1));
+                    spans.push((cursor_scope, range.head..cursor_end));
                 }
             }