Update /README.txt, remove duplicate /doc/README.txt and update CMakeLists.txt to package /README.txt

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

Attempt to fix objects getting multiplicated by objects getting deactivated in a different block than where they were loaded and then the original block, from where the static object was removed, not getting saved at unload

Add a log message to SEnv and make it load objects if there are < 51 of them, to load blocks that were limited to 50