occlusion culling fix, a little reshaping of map rendering for more useful profiler output and dynamic profiler text size

Default max_simultaneous_block_sends_server_total to 2 to make network not cough too much on the fixed block sending code

strict_protocol_version_checking setting; PROTOCOL_VERSION in clientserver.h; clean up defaultsettings.cpp and minetest.conf.example

Collected and moved existing camera infrastructure from game.cpp to camera.cpp and camera.h. Introduced configuration settings 'fov' which chooses the camera's (vertical) field of view and 'view_bobbing' which currently does nothing. Other code refactored to not expect the FOV to be a build time constant.

This is just a chat window with the / text pre-loaded.

Added message of the day and made it properly configurable using /#setting (not saved to config file yet)

Lowered default viewing range minimum to such that it allows fairly good framerate in jungles with sucky hardware.
Almost all computers stick to the minimum with the current farmesh range that someone has set up without asking from me, but farmesh is not used as default anyway so those that use it can raise the lower limit in their configuration as they wish.

New map generator added (and SQLite, messed up the commits at that time...) (import from temporary git repo)