v1.3.0: Data encapsulation and access functions (#69)

* Making MPI communicator variables private in parallelComm, and adding access functions

* Making public variables private in the class tioga, and adding access functions

* Private variables and some access functions for the CartGrid class

* More access functions for CartGrid

* Making m_info and m_info_device in CartGrid private

* Access functions for ilo and ihi in CartGrid

* Making the CartGrid member dims and nf private, and adding access functions

* Conversion to private and adding access functions for xlo and dx in CartGrid

* Access functions for ngrids and donor_frac in the CartGrid class

* Making comm_size const in getCartReceptors()

* Making cart_comm_size const in exchangeAMRDonors() and checkComm()

Performance improvements

Reduce communication overhead in Tioga

v1.0.0

This is the version of the code used to run the Exascale computing challenge problem for Exawind