created global variables and some checking functions
Merge branch 'master' of https://github.com/donachys/simpy
added global variables and integrated simPYcity.m, simPYcity2000.m, simPYcity3000.m, computeIncomes.m, computeNeighborIncomes.m, findBestCity.m, findBestCity2k.m, computeQualityOfLife.m.