Updated various links in docs to avoid redirects

Thanks Tim Graham and Mariusz Felisiak for review and completion.

docs/ref/contrib/gis/forms-api.txt

@@ -7,10 +7,10 @@ GeoDjango Forms API
 
 GeoDjango provides some specialized form fields and widgets in order to visually
 display and edit geolocalized data on a map. By default, they use
-`OpenLayers`_-powered maps, with a base WMS layer provided by `Metacarta`_.
+`OpenLayers`_-powered maps, with a base WMS layer provided by `NASA`_.
 
 .. _OpenLayers: http://openlayers.org/
-.. _Metacarta: http://www.metacarta.com/
+.. _NASA: https://earthdata.nasa.gov/
 
 Field arguments
 ===============

docs/ref/contrib/gis/geos.txt

@@ -18,7 +18,7 @@ and spatial operators. GEOS, now an OSGeo project, was initially developed and
 maintained by `Refractions Research`__ of Victoria, Canada.
 
 __ https://trac.osgeo.org/geos/
-__ http://sourceforge.net/projects/jts-topo-suite/
+__ https://sourceforge.net/projects/jts-topo-suite/
 __ http://www.opengeospatial.org/standards/sfs
 __ http://www.refractions.net/
 

docs/ref/contrib/gis/install/index.txt

@@ -257,7 +257,7 @@ Summary::
     $ brew install gdal
     $ brew install libgeoip
 
-__ http://brew.sh/
+__ https://brew.sh/
 .. _Xcode: https://developer.apple.com/xcode/
 
 .. _kyngchaos:
@@ -402,8 +402,8 @@ install :ref:`postgisasb`.
     and contains shortcuts for the ASB as well as the 'SQL Shell',
     which will launch a ``psql`` command window.
 
-__ http://www.enterprisedb.com/products-services-training/pgdownload
-__ http://www.enterprisedb.com
+__ https://www.enterprisedb.com/downloads/postgres-postgresql-downloads
+__ https://www.enterprisedb.com
 
 .. _postgisasb:
 

docs/ref/contrib/gis/install/spatialite.txt

@@ -133,4 +133,4 @@ following to your ``settings.py``::
 
     SPATIALITE_LIBRARY_PATH='/usr/local/lib/mod_spatialite.dylib'
 
-.. _Homebrew: http://brew.sh/
+.. _Homebrew: https://brew.sh/