Replace `mem_free` by `free`, and `mem_alloc` by `malloc` or `calloc`
(the latter one being used to allocate a zeroed array of elements,
sometimes, this makes a call to `mem_zero` superfluous).
This results in having to remove `mem_stats` which previously recorded
the number of allocations and their size that the Teeworlds code did
directly.
Remove OOM handling in `src/game/client/components/binds.cpp`.
Remove needless copying in the CSV code in
`src/game/client/components/statboard.cpp`.
teehistorian records all inputs from the players as well as the player
positions in each tick. It stores this info in a highly compressible
output format (I've achived 5x compression using xz or bz2).
This system can easily be extended by independent authors without
collisions, something the old system with plain increasing integers did
not allow.
Do this by utilizing the previously unused message code `NETMSG_NULL`
which has a value of 0.
This works for engine and game messages, snapshot items and events.
