make isotypereader reading 4 bytes at a time when reading uint32
make isotypereader reading 4 bytes at a time when reading uint32

git-svn-id: c4d2d6f4036cbf3d898a71de5246e4e6216e7677@659 7decde4b-c250-0410-a0da-51896bc88be6

LoveOpenSource/mp4parser,murat8505/mp4parser,michalliu/mp4parser,godghdai/mp4parser-1,frostwire/mp4parser,rasheedamir/mp4parser,shijian95/mp4parser,agenliuhuan/mp4parser,olegloa/mp4parser,jiangzhonghui/mp4parser-1,hatiboy/mp4parser-1,shs1989/mp4parser-1,sannies/mp4parser