Added sample checkboard
Added sample checkboard

markusgrotz/rtabmap,markusgrotz/rtabmap,srmanikandasriram/rtabmap,markusgrotz/rtabmap,srmanikandasriram/rtabmap,srmanikandasriram/rtabmap,chen0510566/rtabmap,chen0510566/rtabmap,MASKOR/rtabmap,MASKOR/rtabmap,MASKOR/rtabmap,chen0510566/rtabmap