Lib swmm5.lib file added

C/C++ applications that use swmm5.dll need to link their executables to
the swmm5.lib file. The dynamic-link library (dll) for SWMM interfacing
is more powerful for Windows OS than command line. Futher changes in
this project's SWMM interfacing will come soon for using swmm5.dll when
it's Windows instead of command line (the later one will be used for
Linux).