Add base dir for feed entries
Blog: ignore non md or html files
local_data
Update wiki subrepo link and makefile for new platform-blog repo
Use absolute URLs in 'self' links and post images

Feedly is broken and doesn't understand base URLs. We assumed that post
bodies were still relative to the post directory and not the feed
itself. Now absolute URLs are used for both self links and embedded
images. Fixes ocaml/platform-blog#12.
When blog is empty, output valid XML.
O2wPackage: update reverse dependency headings.

Fixes #104.
Separate opam2web application styles from demo site styles.

Also, use a monospace font for opam formula operators.
Use & and | for conjunction and disjunction in formulae rather than logic operators.
Merge branch 'master' into site-merge
Fix bootstrap js loading
Every opam2web site should use opam2web.css

Also, factored more demo-specific style into site.css.