SP-GiST / GiST support for ND contains, within, equals operators

[komzpa]

Patch: ​https://github.com/postgis/postgis/pull/293

[komzpa]

In 17001:

GiST and SP-GiST n-D indexes (based on GIDX) with overlaps, contains, within, and equals operators

Patch by Esteban Zimányi and Arthur Lesuisse from Université Libre de Bruxelles (ULB)

Closes ​https://github.com/postgis/postgis/pull/327
Closes ​https://github.com/postgis/postgis/pull/293
Closes #4230

[komzpa]

In 17002:

GiST and SP-GiST GiST and SP-GiST n-D indexes (based on GIDX) with overlaps, contains, within, and equals operators

Files not added in previous commit.

Patch by Esteban Zimányi and Arthur Lesuisse from Université Libre de Bruxelles (ULB)

Closes #4230

[strk]

The change broke upgrades, please see ​https://drone.osgeo.org/postgis/postgis/1509/3

[komzpa]

In 17005:

Upgrade script generator fix

References #4230

[komzpa]

In 17010:

SP-GiST within got into 3.0.0 not 2.5.0.

References #4230

[komzpa]

In 17012:

[drone] Don't test PostGIS 3.0 on Postgres 9.4

References #4230

[komzpa]

Drone is happy since r17012.