[Proj] Canada NTv2.0 grid shift files

[Mike Toews]

> On Sun, 16 Sep 2018 at 19:48, Saulteau Don <sault.don at gmail.com> wrote:
> Not sure why they got placed under non-free. Maybe it's the liability clause that makes them non-free or not 'true' open data.

While digging around this file, it turns out this file wasn't cheap in 2001:
https://web.archive.org/web/20010227084518/http://cgis.geod.nrcan.gc.ca/products/html-public/GSDapps/English/NTv2_Fact_Sheet.html

CD ROM: $195.00
Developer's License (includes CD-ROM): $995.00
CD-ROM wholesale for re-distribution (minimum 20 units): $50.00
(!)

Nevertheless, anyone can now freely download and use this file. Ensure
this file is file is named lowercase, and put in PROJ_LIB. It should
work with most versions of PROJ (back to version 4.4.7). When
released, ntv2_0.gsb should be part of version 1.2 of the
proj-datumgrid-north-america region-specific package.

Here is Kristian's ticket for OSGeo4W that should get more attention:
https://trac.osgeo.org/osgeo4w/ticket/560