[Backport branch-8-4] expose the embedded OpenLayers lib (for template=openlayers) in a new /extra folder

conf.py

@@ -157,6 +157,12 @@ def __getattr__(cls, name):
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ['_static']
 
+# Add paths that you wish to copy to the output directory
+# see: https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-html_extra_path
+# note that the actual 'extra' folder itself is excluded, so only its contents
+# are copied to the output directory
+html_extra_path = ['./extra']
+
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
 html_last_updated_fmt = '%Y-%m-%d'

en/cgi/openlayers.txt

@@ -100,3 +100,15 @@ Customizing settings
 * environment variables::
 
     MS_OPENLAYERS_JS_URL - The URL to the OpenLayers javascript library. Per default the library loaded from the MapServer web server.
+
+Location of the embedded OpenLayers.js file
+-------------------------------------------
+
+If you aren't providing your own OpenLayers library through `MS_OPENLAYERS_JS_URL`, 
+MapServer will point to a hardcoded filepath of `www.mapserver.org/lib` to find the OpenLayers 
+library, referred to in [maptemplate.c](https://github.com/MapServer/MapServer/blob/main/src/maptemplate.c#L54).
+
+The contents on that `lib` folder is stored in the MapServer documentation repository, 
+in the [/extra](https://github.com/MapServer/MapServer-documentation/tree/main/extra) folder.
+You are warmly encouraged to contribute to upgrading the OpenLayers library, at any time (maybe start 
+with creating a new [Pull Request](https://github.com/MapServer/MapServer-documentation/pulls) there.

extra/lib/README.md

@@ -0,0 +1,23 @@
+# OpenLayers library files for template=openlayers
+
+MapServer's built-in [OpenLayers viewer](https://mapserver.org/cgi/openlayers.html)
+points to a hardcoded filepath of `www.mapserver.org/lib` to find the OpenLayers 
+library, referred to in [maptemplate.c](https://github.com/MapServer/MapServer/blob/main/src/maptemplate.c#L54).
+
+The entire contents of the `lib` folder in this documentation repository 
+will now be copied as-is, when the documentation is built & deployed.
+
+Previously, the `lib` folder containing the OpenLayers library only existed on 
+a server (that could be pruned through various possible steps during the 
+automatic deployment of the MapServer documentation).
+
+# Related 
+
+- [RFC 63](https://mapserver.org/development/rfc/ms-rfc-63.html) (add 
+  Built-in OpenLayers map viewer)
+- initial [issue #3549](https://github.com/MapServer/MapServer/issues/3549)
+
+# History
+
+- updated to OpenLayers 2.10 in 2014
+- initially included in the MapServer 6.0 release in 2011

extra/lib/theme/default/google.css

@@ -0,0 +1,10 @@
+.olLayerGoogleCopyright {
+    right: 3px;
+    bottom: 2px;
+    left: auto;  
+}
+.olLayerGooglePoweredBy {
+    left: 2px;
+    bottom: 2px;   
+}
+

extra/lib/theme/default/ie6-style.css

@@ -0,0 +1,7 @@
+.olControlZoomPanel div {
+    background-image: url(img/zoom-panel-NOALPHA.png);
+}
+.olControlPanPanel div {
+    background-image: url(img/pan-panel-NOALPHA.png);
+}
+