Changed t2t files to markdown (md) files

[nemoyjh]

t2t Files were changed to md files using text2tags.

[inariksit]

Thanks for the initiative @nemoyjh! I have some concern for backwards-compatibility, because links in a TOC generated from the t2t files is different from TOC generated from markdown. Example:

http://www.grammaticalframework.org/doc/gf-video-tutorials.html#general-introduction-to-gf
— link is the name of the subheading. This page was written as a markdown file from the beginning.

http://www.grammaticalframework.org/doc/gf-shell-reference.html#toc8 — link is the word toc + a number.

The thing I'm worried about is that some resources have linked these pages with #tocN and those links are now broken. I can change of course all references from my blog, my StackOverflow answers and on the GF website, but I wonder if there are other sources where those links can't be changed, like the gf-dev mailing list.

[anka-213]

It might be possible to manually insert anchors with the old names into the markdown. Something like this might work:

#### <a name="toc8"></a> cc = compute_concrete 

See this stackoverflow question for more details:
https://stackoverflow.com/questions/5319754/cross-reference-named-anchor-in-markdown