ugh, fine
remove some global vars. reduce scalers down to simple. remove menu.cpp
code.
remove SSE render code. remove SSE check.
remove complex scalar importing and defines
remove complex scalers, force 1x scalar.
remove now unused dynamic core param
bugfix: don't use assert() in SHELL_Init() to range check shell-end vs
mem start IF the shell was allocated in the DOSBox private area / UMB,
because the assertion will fail in that case (segment 0xC8D8, end of
shell, is larger than DOS memory start, which is 0x51).