Added option to make the model fly in particle system demo
Added option to make the model fly in particle system demo

jason-crow/cesium,kaktus40/cesium,oterral/cesium,NaderCHASER/cesium,AnimatedRNG/cesium,emackey/cesium,YonatanKra/cesium,omh1280/cesium,NaderCHASER/cesium,progsung/cesium,oterral/cesium,kiselev-dv/cesium,denverpierce/cesium,YonatanKra/cesium,AnimatedRNG/cesium,likangning93/cesium,CesiumGS/cesium,denverpierce/cesium,CesiumGS/cesium,wallw-bits/cesium,hodbauer/cesium,AnalyticalGraphicsInc/cesium,AnimatedRNG/cesium,progsung/cesium,denverpierce/cesium,CesiumGS/cesium,geoscan/cesium,YonatanKra/cesium,CesiumGS/cesium,aelatgt/cesium,emackey/cesium,omh1280/cesium,kiselev-dv/cesium,jasonbeverage/cesium,AnimatedRNG/cesium,geoscan/cesium,soceur/cesium,wallw-bits/cesium,kiselev-dv/cesium,emackey/cesium,YonatanKra/cesium,soceur/cesium,likangning93/cesium,AnalyticalGraphicsInc/cesium,omh1280/cesium,aelatgt/cesium,aelatgt/cesium,wallw-bits/cesium,jason-crow/cesium,denverpierce/cesium,josh-bernstein/cesium,josh-bernstein/cesium,kiselev-dv/cesium,jason-crow/cesium,likangning93/cesium,likangning93/cesium,oterral/cesium,jasonbeverage/cesium,jason-crow/cesium,ggetz/cesium,kaktus40/cesium,NaderCHASER/cesium,wallw-bits/cesium,omh1280/cesium,hodbauer/cesium,ggetz/cesium,likangning93/cesium,ggetz/cesium,soceur/cesium,CesiumGS/cesium,aelatgt/cesium,hodbauer/cesium,emackey/cesium,ggetz/cesium