Added the hooks needed to make metafile reading asynchronous.
Next I'll change the actual metafile access to work that way. * libnautilus/nautilus-directory.h: * libnautilus/nautilus-directory.c: (nautilus_directory_metadata_call_when_ready): Added function that requests a read of some metadata and calls back when the data is ready. * src/ntl-app.c: (nautilus_app_startup): Got rid of call to nautilus_navinfo_init. * src/ntl-types.h: Moved the NautilusNavigationInfo struct and related defines to ntl-uri-map.h. * src/ntl-uri-map.h: * src/ntl-uri-map.c: Reformatted and changed the names of many functions. Added code to use the new metadata callback. * src/ntl-index-panel.c: * src/ntl-main.c: * src/ntl-view.h: * src/ntl-window-msgs.c: * src/ntl-window.c: * src/ntl-window.h: Had to change includes a bit because of my changes to what header files are including. * src/ntl-window-msgs.c: (nautilus_window_update_state): * src/ntl-window.h: Use the new nautilus_navigation_info_cancel call instead of reaching right in to cancel the underlying call. * src/ntl-view-private.h: Reformatting.