[#2125] Update to pelican build system

Problem
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Styleguide pages was using an outdated hyde build system... which fails when trying to pull deps again.


Changes
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Swich code to pelican which is maintained and has tests.

Beside renaming and a few small changes in templates the migration was lean as pelican is also using RST and jinja2.

Hosting was moved from Dremahost to GitHub pages. This is a big improvement  since now anyone can push the changes. ... Pushing still does not work on Windows due to this bug https://github.com/davisp/ghp-import/pull/23 ... but hope the bug will be fixed soon.

build system was also update to latest paver.sh this is why the changes.

How to test
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reviewers: @alibotean @dumol 
depends-on: #11 

This branch is based on #11 and this is why the diff is bigger... I will ask for review once parent is merged.

Check README... but this is just to let you know about the change.

Thanks!