Text export lua scripts

Fixing /scripts/forum-dwarves.lua to work with 0.40.13 and adding new scripts/markdown.lua which is doing basically the same stuff, but in markdown (for reddit posts)
http://dwarffortresswiki.org/index.php/DF2014:Text_viewer contains a complete list of tokens, if you're interested (namely, `[B]` is equivalent to `[P][P]` or `[R][R]`).