methods to get the index path of a cell for a concrete date and a method to get the cell itself for a date

Signed-off-by: Ruben Mendez <ruben.mendez@gmail.com>
method that calculates index paths between two indexPaths

Signed-off-by: Ruben Mendez <ruben.mendez@gmail.com>
get all index paths to reload depending on selection

Signed-off-by: Ruben Mendez <ruben.mendez@gmail.com>
right calculation of index paths between two limits

Signed-off-by: Ruben Mendez <ruben.mendez@gmail.com>