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.

When first entering an area, sometimes placing nodes replaces other nodes that are not buildable_to. This seems to be caused by the fact that nodes in unloaded map blocks are treated as ignore, a node that is buildable_to. This fixes that, by using get_node_or_nil() instead of the previously-used get_node(), then checking to see if the nodes were actually loaded before replacing.

Spawn single particles or make use of ParticleSpawner for many randomly spawned particles.
Accessible in Lua using minetest.spawn_particle and minetest.add_particlespawner.
Increase Protocol Version to 17.

Conflicts:
	src/clientserver.h

This way flowing liquids actually show the backface when specified to
do so. Without this, TileDefs where by default initialized with
backface_culling = true and never set otherwise.

For backwards compatibility, an old client connected to a new server,
or a new client connected to an old server will behave like before
i.e., backface_culling is always true.

the following:
1. String concatenation in guiMainMenu.cpp - it is required for all
individual strings to be of the same type <unicode/non-unicode>; adding
explicit L qualifier before the other strings.
2. Correcting type of BlockMakeData to struct in place of class forward
declarations. This information is used for name decoration by Visual
Studio, leading to linker errors in case of mismatches.
3. Windows headers define max as a macro somewhere, leading to a compile
time error in profiler.h; using () around function to prevent macro match
from occurring.