Documentation license CC BY 4.0 International

Add copyright and license notices to all significant documentation
Render docs using GFM not standard Markdown

GFM = GitHub Flavoured Markdown
Add text of CC BY 4.0 license

In build.xml, add options to pandoc(1) conversion of Markdown to HTML
for help section, to properly format multi-level lists

Rename LICENSE.md to LICENSE-SOFTWARE.md

Add LICENSE-DOCUMENTATION.md (commons deed) and CC-BY.40.md (legal text)
Remove copyright/license notice from some help pages
add sub-module for srelay; build srelay binary.
add srelay binary to apk
Change submodule url to protocol everyone can read
Remove unused code
First draft of MSP tunnel creation UI
Sync submodules