Update links and clarify versions

doc/users/installing.rst

@@ -10,23 +10,24 @@ Dependencies
 **Requirements**
 
 These are external packages which you will need to install before
-installing Basemap. 
+installing Basemap.
 
 
-Matplotlib 1.0.0 (or later, `download <http://sf.net/projects/matplotlib/>`__)
+Matplotlib 1.0.0 (or later, `download <https://matplotlib.org/users/installing.html>`__)
 
-Python 2.6 (or later, including Python 3)
-    Matplotlib requires Python 3.5 or later (`download <http://www.python.org/download/>`__)
+Python 2.6 (or later, including Python 3) (`download <http://www.python.org/download/>`__)
+    Matplotlib 2.2 LTS requires Python 2.7 or later
+    Matplotlib 3.0 requires Python 3.5 or later
 
 NumPy 1.2.1 (or later)
-    Array support for Python (`download <http://sourceforge.net/project/showfiles.php?group_id=1369&package_id=175103>`__)
+    Array support for Python (`download <http://www.numpy.org/>`__)
 
 `PROJ4 <https://trac.osgeo.org/proj/>`__ Cartographic Projections Library.
 
 **Required library that ships with Basemap**
 
 `GEOS <http://trac.osgeo.org/geos/>`__ (Geometry Engine - Open Source) library 3.1.1 or later.
-    Source code is included in the geos-3.3.3 directory. 
+    Source code is included in the geos-3.3.3 directory.
     When building from source, must be built and installed separately
     from basemap (see build instructions below).
     Included in Windows binary installers.
@@ -40,8 +41,8 @@ Pillow
 Installation
 ============
 
-Download either Windows binary installers or source tarballs 
-`here <https://github.com/matplotlib/basemap/releases/>`__. 
+Download either Windows binary installers or source tarballs
+`here <https://github.com/matplotlib/basemap/releases/>`__.
 
 To install from the source, follow these steps:
 
@@ -52,7 +53,7 @@ To install from the source, follow these steps:
   and cd to the basemap-X.Y.Z directory.
 
 * Install the GEOS library.  If you already have it on your
-  system, just set the environment variable GEOS_DIR to point to the location 
+  system, just set the environment variable GEOS_DIR to point to the location
   of libgeos_c and geos_c.h (if libgeos_c is in /usr/local/lib and
   geos_c.h is in /usr/local/include, set GEOS_DIR to /usr/local).
   Then go to next step.  If you don't have it, you can build it from
@@ -62,7 +63,7 @@ To install from the source, follow these steps:
       export GEOS_DIR=<where you want the libs and headers to go>
       # A reasonable choice on a Unix-like system is /usr/local, or
       # if you don't have permission to write there, your home directory.
-      ./configure --prefix=$GEOS_DIR 
+      ./configure --prefix=$GEOS_DIR
       make; make install
 
 * cd back to the top level basemap directory (basemap-X.Y.Z) and