Optimize CNodeDefManager::getIds
Fix MapgenV6::generateCaves possible division by 0 and misc. cosmetic fixes
Install locales in minetest directory, so they are correctly loaded
Don't grant priveleges to non-existent players.

When accidentally misspelling a name, privileges are sometimes granted to non-existent players, leaving them with the extra privileges, but without the default privileges, if they ever join the server. This corrects that by disallowing /grant from working with invalid players. For completeness, it does the same for /revoke.
Don't load menu textures every frame
Add a small optimization to the menu splash and remove a old comment
Add Kyrgyz language
Increase value range of Ore::clust_scarcity
Add Ore generation flags, implement ore absolute height
Return an ItemStack in minetest.item_place() if nodes' on rightclick doesnt return it
Merge 'upstream/master' into patch-3