Cleanup in progress

I've cleaned up a few things that were annoying me.

I fixed exporting to use a C# style attribute syntax, so now you use

    [export := header.function]
    f() {}

I fixed constructor member initialization syntax to support identifying bases by type.
I fixed resolving overloads based on lvalue/rvalue w.r.t. ref-qualifiers in C++.
I fixed auto-detecting Linux includes (boy, not having that was super annoying).
I implemented exception re-throwing with throw;.

Next up on my list is parsing and lexing. My current parser and AST are fairly kludgy- their design is from way back when I parsed multiple files directly into the same AST concurrently, didn't support operator overloads, and the parser's lexer interface is from years ago also. The lexer itself isn't too bad but I just need to alter the token types a bit.

The main reason for this is that the parser doesn't support dynamic destructors, or dynamic operators, or defaulted/deleted functions, etc, and the design is non-conducive to being modified at run-time. There's also some duplicate code in terms of rules operating in terms of what other rules expect and the error handling is quite duplicated.

The new approach will be half table-driven, half recursive descent. And the AST/Builder will be changed to not stringly type destructors, constructors, and not indicate operators by token type, etc. The main change for the lexer will be that it will no longer be a token type enumeration. Instead token types will be indicated by a constant pointer (probably to std::string). This allows new token types to be added. In addition the lexing tables will be made members of the lexer instance to permit modification instead of constant as they are now, as will the parsing tables.