fix: don't let control characters mess up the display

Before:

    ╭─ CommandT [file] ────────────────────────────────────────────╮
    │>                                                             │
    ╰──────────────────────────────────────────────────────────────╯
    ╭──────────────────────────────────────────────────────────────╮
    │>                                                             │
    │↳ Icon^M                                                      │
    │↳                                                             │
    │  brew.rb                                                     │
    │  ...etc                                                      │
    ╰──────────────────────────────────────────────────────────────╯

After:

    ╭─ CommandT [file] ────────────────────────────────────────────╮
    │>                                                             │
    ╰──────────────────────────────────────────────────────────────╯
    ╭──────────────────────────────────────────────────────────────╮
    │> Icon\r                                                      │
    │  brew.rb                                                     │
    │  ...etc                                                      │
    ╰──────────────────────────────────────────────────────────────╯

Note that this is a display-only thing, to stop undesired wrapping and
other visual distortions. You can't actually type "Icr" and expect it to
match the file (these is no "r" in the name), although you can open it
by accepting the selection.

Closes: #402

lua/wincent/commandt/private/match_listing.lua

@@ -46,6 +46,16 @@ end
 local format_line = function(line, width, selected)
   local prefix = selected and '> ' or '  '
 
+  -- Sanitize some control characters, plus blackslashes.
+  line = line
+    :gsub('\\', '\\\\')
+    :gsub('\b', '\\b')
+    :gsub('\f', '\\f')
+    :gsub('\n', '\\n')
+    :gsub('\r', '\\r')
+    :gsub('\t', '\\t')
+    :gsub('\v', '\\v')
+
   -- Right pad so that selection highlighting is shown across full width.
   if width < 104 then
     if #line > 99 then