Check if mesh is here before adding to meshcollector.

Fix deleting the meshes.

sky.cpp: m_bgcolor.getAlpha() was being used before initialised

mesh related: m_highlight_mesh_color was being used uninitialised

pause menu

Fix android build using hardcoded path for data instead of using the one fetched by android api on init.
Fix android missing version information

Fixes: http://i.imgur.com/arAWw1i.png (middle-right)

Broken by 6bc4cad0, e.g.
  minetest --worldname world
would be parsed as
  minetest --worldname --worldname

Broken by 6bc4cad0 because database-redis.h
depended on settings.h to include filesys.h.