Nllgrid

- Fix bug preventing writing a newly created grid to a file, when the grid
`float_type` was not explicitly set

- Fix for missing test data in PyPI package

- Fix for PyPI publishing

- `NLLGrid.horizontal_recenter()` method to move the (x, y) origin of grid
cartesian system to the grid center
- `NLLGrid.horizontal_rotate()` method to rotate the grid horizontally around
its center
- `NLLGrid.nudge()` method to expand or contract in any direction a grid
- Added `TRANS_MERC` and `AZIMUTHAL_EQUIDIST` projections
- Fix projections when `map_rot != 0`

- Still another fix for version string

- Fix version string reported by `nllgrid.__version__`