Restore the project documentation

[ForNeVeR]

(Extracted from #11).

Help and docs directories store some HTML sources and compiled chm files. We need to decompile these files and store the docs in some more friendly manner. Also we'll need to import the current documentation from the preserved online copy.

• Download a copy of the latest official online documentation and store into a repository
• Decompile jabber-net.chm file, extract the information from it, and delete the file
• Extract the information from the docs directory and delete the directory
• Extract the information from jabber-net-helpfilebuilder.shfb file (if any; probably there're namespace comments) and delete it
• Merge all the documentation and store it in some modern format such as Markdown (in that case we'll want to use Jekyll or FSharp.Formatting to prepare the user-accessible documentation)
• Decide if we want to store the API reference somewhere on site (it seems that everyone does that, even if I don't like it), and if so then how to do it (I've seen some great documentation examples made with F# and FSharp.Formatting)
• Add a reference documentation
• Actualize the documentation (after conversion it's still slightly outdated)
• Publish the documentation online (probably using a GitHub Pages)