Fix for NB#59458 (should dim sort button when the selected folder

Fix for NB#59458 (should dim sort button when the selected folder
is a root folder).
* src/maemo/modest-main-window-ui-dimming.h:
        * Added dimming handler for sort dialog actions.
* src/modest-ui-dimming-rules.[ch]:
        * Added dimming handler for sort dialog actions. Should
          be dimmed when the folder is a root folder.

Restored the UI menu actions available in viewer.
* src/maemo/ui/modest-msg-view-window-ui.xml:
        * Readded show toolbar actions.
        * Readded find in page actions.

pmo-trunk-r2147