Panos Mavrogiorgos 0c3cb558a8 Introduce GRASS_USE_REXTERNAL setting
GRASS GIS, in addition to importing data in its native formats via
`r.in.gdal`/`v.in.ogr` (and likewise `r.import`/v.import`),
also supports `r.external`/`v.external` which only link the data into
the GRASS DB.

Nevertheless, both `r.external` and `v.external` occasionally have problems,
especially on windows. E.g.:

- https://trac.osgeo.org/grass/ticket/3927

GRASS 7 Processing Plugin already has a setting that controls whether
`v.external` is used (disabled by default).

With this commit the complementary setting for `r.external` gets added too.
Usage of `r.external` is disabled by default. This is changing the existing
behavior, which was to use r`r.external`. The downsides of this change
should be the somewhat lower import speed + higher disk usage. Nevertheless
this way we have the same default value as `v.external` + we circumvent the
`r.import/v.import` shortcomings.
2020-01-02 18:26:49 +10:00
..
2019-10-26 10:50:30 +10:00