generalized the data reshaping process

use indexing to reshape even with missing data
rename ConstructData.m to ConstructDataGroup.m

prepare it to become a function
restructure the data construction process

separate the old ConstructData.m script into 2 files
- function ConstructDataGroup.m reshapes the balanced dataMatrix into dataR structure
- script ConstructData.m group data according to choicesets and send them to
ConstructDataGroup.m for reshaping