Port to Microsoft Visual C++ 6.0 (VC6)

[IAmTrial]

The entire codebase is to be ported to a VC6 project. SGD2FreeRes is expected to link to the SGD2MAPI98 library.

There are some advantage of VC6. The VC6 runtime is included in nearly all versions of Windows. The compiler is also period-accurate for Diablo II. Compile times are significantly shorter and file sizes tend to be smaller.

Some disadvantages were considered, but would be worked around or remedied. The lack of C++11 and C99 features means having to rewrite some of the code to compile under the older standards.

This porting should still allow code to be compiled with a more modern C++ compiler. Features that have been deprecated and/or removed in a modern C++ revision should be avoided. The software should behave similarly to before.