Fix linking with Boost if C++ versions don't match

BOOST_SCOPED_ENUM is implemented differently in C++11 mode

This means that Boost.Filesystem ABI depends on what C++ version was
used to compile the library. This commit checks for that and forces
the correct BOOST_SCOPED_ENUM implementation.
Use correct include file for pthread_set_name_np

This allows setting thread names on FreeBSD.
Fix a typo in README.md

How long has this been in here?
Tweak README.md
Put log file path on its own line in error dialogs

... to prevent stretching the dialog box.
Remove unused function FirstPolyPosY
Use getter for fast background data
Ensure pthread is linked for pthread_* checks
Don't statically link libgcc with USE_STATIC_LIBS
Don't include .rc files in untity build

They don't contain C++ code and need to be compiled separately.
Fixes unity build with MinGW.
Move entity speed modifier calculation to one place
Cleanup 2D bounding box calculation
Unify copy-paste
Unify copy-paste
Move call to render animated object into EERIEDrawAnimQuat
Remove 2d bounding box culling
Remove 2d bounding box culling, for static objects
Continue early on false preconditions
Indentation
Remove distance based culling from RenderInter