"aux1_descends" setting switches to the old descend control.

Fullscreen, vsync, fullscreen_bpp and fsaa options in the config; fsaa is experimental atm, causes visible spaces between blocks.

Defaults modified from original: alpha=200, key=F10

Remove stuff made obsolete by making players more ActiveObject-like and raise protocol version number by one (because it is not compatible at all anymore)

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