Adding support for Scottish Gaelic (gd)

[anjackson]

I work with national libraries in the United Kingdom. We've been very happy with your Welsh language detection, and would like to add support for Scottish Gaelic.

In this repository I've generated a gd language profile from texts supplied by the National Library of Scotland (they can't be openly licensed unfortunately, so they are not in the repository).

The language profile is here: https://github.com/ukwa/language-profile-creation/blob/master/profile-output/gd

I tuned the minimum N-gram frequency up to 50 in order to get the profile down to about 30KB in size. If you'd like a different size/configuration please let me know.

[anjackson]

Hello again. I'm happy to reformat this in any way you need, so it can be included. Just let me know.