Make it a bit easier to work on website

`python make website` gives the commands you can use, but also
emmediately clones the website repository

`python make images` clones the images repository so that the
website builder can build the gallery.
WIP: Add JFA example
FIX: Filename
FIX: Fix viewport [ci skip]
FIX: Multiple fixes
FIX: Fix organization [ci skip]
FIX: Fix problems [ci skip]
FIX: Cleaner [ci skip]
FIX: Fix examples
FIX: Fix Framebuffer and examples
FIX: abspath
FIX: Py3k
FIX: Fix coverage
FIX: Fix with call [ci skip]
Merge pull request #330 from Eric89GXL/jfa

ENH: Example of translating existing project
Added two examples: 3D brain viewer, and multichannel digital signal viewer.
Updated examples.
Merge pull request #312 from almarklein/easier-make-website

Make it a bit easier to work on website
Removed deprecated syntax in Python 3.
Added elapsed property to Timer class and to timer_timeout event.