Used boost libraries

Much code in KlayGE depend on Boost. Here's the list of used libraries.

The used Boost libraries that must be built separately:

• Filesystem (Can be replaced by TS's or C++17's in msvc and gcc.)

Header-only Boost libraries:

• Algorithm/string
• Any (C++17)
• Assert
• Container/flat_map
• Core/noncopyable
• Optional (C++17)
• TypeIndex
• Utility/Operators
• Utility/string_view (C++17)

Items marked as bold font can be replaced by features in C++11 or C++17. Along with the popularize of C++11/17-supported compiler, those libraries are switched to C++11's or C++17's. Boost libraries are used only when necessary.