* modest-header-view.[ch]:

* modest-header-view.[ch]:
  - refactoring (move display_address -> text_utils)
  - add modest_header_view_get_folder
* modest-folder-view.[ch]
  - change signal from 'folder_selected' -> 'folder_selected_changed',
  so we get also a signal for the folder that is unselected, and
  can save it's settings etc.
  - make modest_folder_guess_folder_type a public and *class* function
* modest-toolbar.c:
  - small cleanups

pmo-trunk-r531