added checks for some possible Divisions by zero
added checks for some possible Divisions by zero


git-tfs-id: [https://tfs.codeplex.com/tfs/TFS05/]$/ZXingNet/trunk;C81139

bsoja/ZXing.Net,DHMechatronicAG/ZXing.Net,micjahn/ZXing.Net,micjahn/ZXing.Net,micjahn/ZXing.Net,DHMechatronicAG/ZXing.Net,bsoja/ZXing.Net,bsoja/ZXing.Net,DHMechatronicAG/ZXing.Net