- added uniform virtual memory allocation
(supports mmap(), vm_allocate(), or fallbacks to malloc()/free())
- cleaned up memory allocation in main_unix.cpp
- Cleaned up the process for determining the ranges of pages touched
that have to be blitted onto the screen (find_next_page_set() and
find_next_page_clear() functions)
Changes made to do_handle_screen_fault()
- An unhandled address is now dealt by the default SIGSEGV handler
- Print out the address of the instruction that caused the exception
but doesn't actually close the window to prevent Basilisk II from being
accidentally killed without a proper shutdown of MacOS
- replaced many #ifdef HAVE_PTHREADS constructs with LOCK/UNLOCK macros
- minor cleanups
- a little loop optimization when clearing the dirty pages
- changed unsigned longs with the uintptr type
- also used uintpr for the page alignment function
