[enhancement] Optionnal direct access for external WMS layers - #34
[Enhancement] Option to publish layers with no legend display in the tree
Enhancement - Get tile from parent project for embedded layers/groups

* The use can configure the lizmap repository in the plugin Lizmap for each embedded layer or group
* The qgis parent project is also configured in the plugin
* This option can be used to share the tile cache between projects
Minor change when testing if a layer is embedded from another project
Map.js - deactivate new OL 2.13 TileManager (white tiles on panning)
Openlayers - re-define image reload attempt for 2.13
Debug map.js
[debug] Keep slash between project path and project file (windows)