On MSVC, casting i32 to i64 then multiplying gets compiled into a call
to __allmul, which is slow. Use the __emul intrinsic instead.
GCC 4.6+ appears optimise this case automatically and doesn't need any
special handling.
This reduces the cost of ComputeShortPath by about 50% (testing AI vs AI
on Oasis 01).
This was SVN commit r13873.
Giant merge from
http://svn.wildfiregames.com/hg-source/file/5fb522019d5e
Infrastructure is largely complete, gameplay is largely missing
Disabled by default; use command-line flag "-sim2"
(Second attempt at commit...)
This was SVN commit r7259.
