[REF] FileGalLib: rename getTreePhplayers() to getTree and getFilegalsTreePhplayers() to getFilegalsTree
[REF][ENH] File galleries module: use getSubGalleries() to get tree nodes, giving back a phpLayers-like tree
[REF] FileGalLib: Remove now unused _buildTreePhplayers(), just generate path from getTree() instead
[REF] Various (Smarty tree)