Adding aliases

[RachamimYaakobov]

New aliases: 'hh', 'hxx', 'cxx'

[marcoscaceres]

Could you help me understand the rationale for adding these? Are they part of c++ standard or common file extensions?

[RachamimYaakobov]

There is a lot of C++ code written in these files,
When I extract from such a file several lines highlight.js does not recognize the language
And you have to tell him explicitly that this is C++, so I just do it through the file extension,
Therefore, highlight.js must know all the extensions.

[marcoscaceres]

Ok, did some additional research and indeed they are commonly used.