Adding GetProj4 request in lizmap service

Sometimes data has USER author id. To use it with vector data, we need
to access its proj4 definition. We added a request in lizmap service and
we updated Proj4js
Using canvas color for the map background

In some map the user defined a background color for the QGIS canvas. Now
LizMap Web Client reused it for the web map.
Edition - handle views & QGIS Where clauses