[gedit] (4 commits) ...search and replace: use async functions

[Sébastien Wilmet <swilmet src gnome org>]

Summary of changes:

  161dd8c... Deprecate gedit_utils_escape_search_text() and unescape() (*)
  5da7ef3... spell: use gtk_source_buffer_search_replace_all() (*)
  c51d3d9... GeditDocument: emit the search-highlight-updated signal (*)
  1a965fc... search and replace: use async functions (*)

(*) This commit already existed in another branch; no separate mail sent