TreeTableView -> TreeView (only-Model concept) interface change.

TreeTableView (as UIView sibling concept) vanished out.
On the other hand TreeTable was born as pure DataSource + Delegate concept.
TreeTable serves as Proxy between UITableView and Controller that implements Delegate & DataSource protocols.
TreeTable is pure UITableViewDataSource only.

TreeTable implements UITableViewDataSource protocol only and
converts 2d UITableView-like indexPaths into TreeView multidimentional indeces.
TreeView forwards @optional messages to Original delegate.

TreeView implemented @required UITableViewDataSource methods only
and forwards all @optional to Original DataSource (usually ViewController)
if it implements any.
Sections support added.

With sections support cells reside in [n, k] indeces and can have its children.
No cells of [m] indeces anymore (treated as section).

Example data change:
PlanetsStore clumsy dataSource vanished out.
Easy.plist introduced with super-easy multilevel structure.
Description updated.