Add some sanity checks: do not read after the string data if the string is not correct...
Add some sanity checks: do not read after the string data if the string is not correct...

Distrotech/librevenge,cpjreynolds/libwpd,Distrotech/librevenge,Distrotech/librevenge,Distrotech/librevenge,cpjreynolds/libwpd,cpjreynolds/libwpd,Distrotech/librevenge