Merge branch '1977_mcedit_type_accuracy' into 4.8.1-stable

Merge branch '1977_mcedit_type_accuracy' into 4.8.1-stable

* 1977_mcedit_type_accuracy:
  Avoid compiler errors about comparsion signed and unsigned variables
  (is_aligned_on_a_tab): return gboolean instead of int. Minor optimization.
  Use off_t instead of long for all variables related to position in file:
  Use long for line numbers and columns.
  (edit_drop_hotkey_menu): return gboolean instead of int.
  (edit_translate_keys): return gboolean instead of int.
  (edit_find_word_start): return gboolean instead of int.
  (edit_save_cmd): return gboolean instead of int.
  (edit_copy_to_X_buf_cmd): return gboolean instead of int.
  (edit_save_block): return gboolean instead of int.
  (editcmd_dialog_raw_key_query): take gboolean instead of int.
  (edit_mark_cmd): take gboolean instead of int.
  WEdit::caches_valid: change int to gboolean.
  (is_in_indent): refactoring, return gboolean instead of int.
  Ticket #1977: type accuracy of WEdit members and mceditor functions.