Fix warnings in io/lzf_image_io.cpp
Fix warnings in io/lzf_image_io.cpp

> lzf_image_io.cpp:243:21: warning: comparison of integers of different signs: 'int' and 'unsigned int' [-Wsign-compare]

jeppewalther/kinfu_segmentation,DaikiMaekawa/pcl,msalvato/pcl_kinfu_highres,jeppewalther/kinfu_segmentation,nh2/pcl,LZRS/pcl,damienjadeduff/pcl,drmateo/pcl,sbec/pcl,closerbibi/pcl,msalvato/pcl_kinfu_highres,kanster/pcl,krips89/pcl_newfeatures,drmateo/pcl,stfuchs/pcl,ipa-rmb/pcl,locnx1984/pcl,fanxiaochen/mypcltest,zhangxaochen/pcl,the-glu/pcl,mikhail-matrosov/pcl,lydhr/pcl,cascheberg/pcl,lydhr/pcl,DaikiMaekawa/pcl,srbhprajapati/pcl,the-glu/pcl,wgapl/pcl,fanxiaochen/mypcltest,DaikiMaekawa/pcl,mikhail-matrosov/pcl,simonleonard/pcl,zavataafnan/pcl-truck,v4hn/pcl,kanster/pcl,MMiknis/pcl,stefanbuettner/pcl,mikhail-matrosov/pcl,v4hn/pcl,pkuhto/pcl,KevenRing/pcl,ResByte/pcl,cascheberg/pcl,damienjadeduff/pcl,simonleonard/pcl,nh2/pcl,stefanbuettner/pcl,KevenRing/vlp,pkuhto/pcl,chatchavan/pcl,KevenRing/pcl,wgapl/pcl,kanster/pcl,nh2/pcl,zhangxaochen/pcl,fanxiaochen/mypcltest,locnx1984/pcl,srbhprajapati/pcl,MMiknis/pcl,chenxingzhe/pcl,MMiknis/pcl,pkuhto/pcl,closerbibi/pcl,stefanbuettner/pcl,fanxiaochen/mypcltest,ResByte/pcl,lydhr/pcl,LZRS/pcl,jakobwilm/pcl,simonleonard/pcl,fskuka/pcl,lebronzhang/pcl,locnx1984/pcl,raydtang/pcl,3dtof/pcl,mikhail-matrosov/pcl,closerbibi/pcl,shyamalschandra/pcl,RufaelDev/pcc-mp3dg,KevenRing/pcl,zavataafnan/pcl-truck,mschoeler/pcl,jakobwilm/pcl,krips89/pcl_newfeatures,fskuka/pcl,lydhr/pcl,raydtang/pcl,locnx1984/pcl,jakobwilm/pcl,chenxingzhe/pcl,cascheberg/pcl,chatchavan/pcl,lebronzhang/pcl,shyamalschandra/pcl,stfuchs/pcl,soulsheng/pcl,msalvato/pcl_kinfu_highres,fskuka/pcl,mschoeler/pcl,shangwuhencc/pcl,zavataafnan/pcl-truck,pkuhto/pcl,drmateo/pcl,3dtof/pcl,zhangxaochen/pcl,zavataafnan/pcl-truck,v4hn/pcl,KevenRing/vlp,sbec/pcl,msalvato/pcl_kinfu_highres,3dtof/pcl,jakobwilm/pcl,damienjadeduff/pcl,zavataafnan/pcl-truck,sbec/pcl,wgapl/pcl,closerbibi/pcl,KevenRing/vlp,msalvato/pcl_kinfu_highres,soulsheng/pcl,KevenRing/pcl,shangwuhencc/pcl,ipa-rmb/pcl,lebronzhang/pcl,shivmalhotra/pcl,shangwuhencc/pcl,stfuchs/pcl,shangwuhencc/pcl,kanster/pcl,LZRS/pcl,starius/pcl,stfuchs/pcl,LZRS/pcl,nikste/pcl,fskuka/pcl,lebronzhang/pcl,drmateo/pcl,raydtang/pcl,DaikiMaekawa/pcl,locnx1984/pcl,drmateo/pcl,ResByte/pcl,fskuka/pcl,the-glu/pcl,krips89/pcl_newfeatures,shyamalschandra/pcl,srbhprajapati/pcl,starius/pcl,shyamalschandra/pcl,LZRS/pcl,RufaelDev/pcc-mp3dg,shangwuhencc/pcl,DaikiMaekawa/pcl,stefanbuettner/pcl,Tabjones/pcl,raydtang/pcl,mschoeler/pcl,srbhprajapati/pcl,jeppewalther/kinfu_segmentation,zhangxaochen/pcl,lydhr/pcl,ResByte/pcl,shyamalschandra/pcl,stefanbuettner/pcl,shivmalhotra/pcl,raydtang/pcl,the-glu/pcl,nikste/pcl,kanster/pcl,MMiknis/pcl,Tabjones/pcl,stfuchs/pcl,srbhprajapati/pcl,mschoeler/pcl,closerbibi/pcl,chatchavan/pcl,fanxiaochen/mypcltest,nikste/pcl,KevenRing/vlp,ipa-rmb/pcl,shivmalhotra/pcl,soulsheng/pcl,chenxingzhe/pcl,chenxingzhe/pcl,soulsheng/pcl,damienjadeduff/pcl,nikste/pcl,starius/pcl,lebronzhang/pcl,shivmalhotra/pcl,Tabjones/pcl,nikste/pcl,jeppewalther/kinfu_segmentation,v4hn/pcl,sbec/pcl,RufaelDev/pcc-mp3dg,jeppewalther/kinfu_segmentation,soulsheng/pcl,mschoeler/pcl,ipa-rmb/pcl,zhangxaochen/pcl,simonleonard/pcl,mikhail-matrosov/pcl,chenxingzhe/pcl,simonleonard/pcl,krips89/pcl_newfeatures,krips89/pcl_newfeatures,cascheberg/pcl,wgapl/pcl,damienjadeduff/pcl,v4hn/pcl,3dtof/pcl,jakobwilm/pcl,shivmalhotra/pcl,KevenRing/vlp,pkuhto/pcl,RufaelDev/pcc-mp3dg,MMiknis/pcl,KevenRing/pcl,Tabjones/pcl,wgapl/pcl,starius/pcl,ipa-rmb/pcl,nh2/pcl,ResByte/pcl,Tabjones/pcl,the-glu/pcl,3dtof/pcl,RufaelDev/pcc-mp3dg,chatchavan/pcl,cascheberg/pcl,sbec/pcl,starius/pcl