Handle new scope names for C++, Objective-C++

[maxbrunsfeld]

In the next release of Atom (v0.166), the scope name for C++ and Objective-C++ will change from source.c++ and source.objc++ to source.cpp and source.objcpp. This is being done to work around some issues with CSS classes containing '+' characters.

This means that for your xikij grammar to continue to support embedded C++, you'll need to add an include for the source.cpp grammar to this section. You probably want to keep the existing include, for backwards-compatibility with versions of Atom < 0.166.

I thought I'd better let you do it yourself rather than submit a PR because I see you have some code to generate the grammar for you.

Nice work on this package, sorry to change things out from under you!

Refs atom/language-c#54.