Fixed MakeMgrepDict empty string error.
Fixed MakeMgrepDict empty string error.

If the label/synonym contains empty string, ignore the such label/synonym.
e4ong1031/ontobee,e4ong1031/ontobee,OntoZoo/ontobee,e4ong1031/ontobee,OntoZoo/ontobee,e4ong1031/ontobee,ontoden/ontobee,ontoden/ontobee,OntoZoo/ontobee,ontoden/ontobee,OntoZoo/ontobee