Merged enttools patch to new engine branch.

In old Xash fork we had a feature, which helps on debugging mods and experiment with entities called enttools.

This is basically an analogue of Source's ent_create & ent_fire, but it also has a function to query entity information back to client.

Some of our users combined it with cvar expansion extension and customizable touchscreen controls to have very basic and generic sandbox mode for every game.