Sciter extensions, SOM, and more

Changes since 0.5.39:

• sciter::graphics
• sciter::request
• sciter::om - support SOM
• SciterLibraryInit - support NSE
• sciter::windowless - support Sciter.Lite windowless builds
• Load sciter.dll from a custom path
• Macros for array/map JSON creation
• Archive handler for resources
• Add sciter::api_version for ABI compatibility versioning