reorganize Terrain/PhysicsWorld/GameState/Engine to use NetworkClientConnect, and hence handle the connection process asynchronously, and finally properly implement receiving the terrain data from the server

syntax: regexp

^build/(CMake|cmake|Makefile|data|doc|src|install_manifest\.txt)
\.[^/]+\.sw[op]$
^doc/kishna.(aux|log|pdf|toc)$
^doc/(html|latex)