Version 0.5.0

Lots of changes, here we mainly change release tag to mark the
important change in mesh handling (using variant instead of interface)

Revise clang-format choices

New version (pastis is now pugs)

Release 0.3.0

- add ItemValue and SubItemValuePerItem
- add Array<T> to embed Kokkos::View
- Kokkos mechanisms are now encapsulated

Improved connectivity management

- Connectivity uses a CRS approach
- Definition of sub item values per items is generically available

Glace scheme is functional for 1d, 2d and 3d calculations

Test avec Kidder pour etude convergence et erreur

- clean-up in progress
- trying to converge to a simple model
- reorganized source tree

First test using Kokkos and code improvements

- Fixed git revision info
- Removed cmake-modules (not used and potentially confusing)
- Implemented 4 versions of the Acoustic solver -> learning Kokkos behavior
- Added Backtrace infos (demangling C++ functions)

Git revision info, CLI11 and Rang

CMake allows now to compute correctly pastis git revision info

New subrepos
- CLI11: command line interpreter
         (https://github.com/CLIUtils/CLI11)
- Rang: colors in terminals
         (https://github.com/agauniyal/rang)
- cmake-modules: bunch of cmake utilities
         (https://github.com/rpavlik/cmake-modules)

A beginning is a very delicate time...

Simplest kokkos plugging