V3 fixes

Hi,
I propose the correction for two bugs I found using the NuGet version of JoinSqlBuilder. To me the resolution of those bugs is crucial so I hope my fixes could bring to a correction. Don't know if the solution I submit is the optimal one, but it works well in my cases. Being my first time here I request a pull instead of directly merging changes, because I also would like a second opinion about my fixes. Don't hesitate to ask for further testing, I have a very realistic test project to play with. Thanks a lot.