HedgeLib++ - Support same archiving formats as C# HedgeLib

[Radfordhound]

Specifically, this means HedgeLib++ should be able to do all of the following:

• [ ] Read Heroes/Shadow Archives (.one)
• [ ] Read '06 Archives (.arc)
• [X] Read Unleashed/Generations Uncompressed Archives (.ar, .pfd) [e21ef448b89e929fe679558969e64f15b3bfaa4f]
• [ ] Read Unleashed/Generations Packed File Indices (.pfi)
• [X] Read Forces Archives (.pac) [16a24c0acd86484d28f4418cd145c017e81fa024]
• [ ] Write Heroes/Shadow Archives (.one)
• [ ] Write '06 Archives (.arc)
• [X] Write Unleashed/Generations Uncompressed Archives (.ar, .pfd) [19b25e42c6d19109b6e6d1e9ad38d0ecab1cb0e6]
• [ ] Write Unleashed/Generations Packed File Indices (.pfi)
• [X] Write Forces Archives (.pac) [d72cbbb22be180ce5499f1e0736e8d5489a75208]

Additional archiving formats (such as Lost World's/Colors', and support for Compression in Unleashed/Generations Archives) are planned to be supported as well, but these were not supported in C# HedgeLib, so they'll have their own issues.