Another update to the documentation - add Halogene's Newbie Corner (fix #227 and #228)

Closes #227 and #228

See merge request !39

This reverts commit 4d77ee73

Since Halogene's Newbie Corner is now in the docs master, no need for basics.aft, which was left uncompiled anyway.

Update the documentation and replace faq.html with a Markdown copy of the website FAQ

Closes #220

See merge request !38

At least two of these no longer exist in Xonotic. Not sure what to do with final_rage (different id) and reslimed (remade as afterslime)

Simplify faq.markdown, removing references to other pages on xonotic.org for now and moving to the main directory

The branch then will be retried until complete, and skipped in the future only then.

Map screenshot server: when downloading maps for a branch fails, still try screenshotting other branches.

The previous code emitted only a MIDI event for the first channel - but
we need one for all.