Alot of stack and event variables are pointers. Align the size of
all script and event variable types to sizeof(intptr_t) so that
the CPU needs only one fetch insn on 64bit archs.
Tested on x86 and x86_64 and found no different script behaviours
compared to the binary from id.
Savegames on x86_64 do work, but are not compatible to x86 and vice
versa (among other issues, the stack is written to file as-is).
x86 builds can still load savegames from the official binary and
vice versa.
