* now getDataAtRow method should returns correct data
* I've added also 2 method to API: getSourceDataAtRow(row) and getSourceDataAtCol(col) to returns original data
refs #1619
some simplification of the getDataAtRow. refs #1619
code cleanup
cleanup getDataAtCol, getDataAtProp
change data for sorting demo
Merge branch 'feature/issue-1619' into develop