* [vcpkg] Consolidate several internal parsers together (packagespecs + logicexpression + control) and enhance error messages
* [vcpkg] Migrate Build-Depends parsing to new framework
* [vcpkg] Fix tests. Re-enable underscores in feature names due to libwebp[vwebp_sdl] -- todo: rename this feature and remove underscores.
* better logic expression evaluation
Improve the logic expression evaluation currently used when filtering
dependencies.
Biggest improvements:
+ Allow '|' operator
+ Support nested '()'
+ Allow whitespace
+ Useful error message for malformed expressions
Also changed names of types to RawParagraph when that is what the original author was using.
