Cell/Struct Tree, and Struct Sorting

Given a cell or a struct, is is sometimes usefull to know the tree from the main to the farthest branch.
The trees are returned as string cells, based on the data type. Each path can be effectively executed using Matlab built-in eval() function.

The sorting of struct is also implemented, with some limitations.
Sorting is achieved based on Matlab built-in sort() function, in reference to one of the fields. Therefore all fields should have equal number of elements.

Sorting cells in relation to one of the field is not implemented.