Fix:core:Complete rename navit_vehicle_update -> navit_vehicle_update_position from r5954.

git-svn-id: svn://svn.code.sf.net/p/navit/code/trunk@5973 ffa7fe5e-494d-0410-b361-a75ebd5db220
Fix:core:Check if speech output is available, to avoid crashing.

git-svn-id: svn://svn.code.sf.net/p/navit/code/trunk@5974 ffa7fe5e-494d-0410-b361-a75ebd5db220
Add:osd:Log error if toggle_announcer configured but no speech available.

git-svn-id: svn://svn.code.sf.net/p/navit/code/trunk@5975 ffa7fe5e-494d-0410-b361-a75ebd5db220