Ensure all features are documented in the manual

[ftomassetti]

I started from removing the list of options from the README and ensure the list in up to date in the manual.

We were missing ~10 options :D

[ftomassetti]

In the README we state "Libjpeg, libtiff and zlib are required by Pillow"
Should we remove this?

[psi29a]

I think these are no longer necessary. However the number of libs required by GDAL is immense... we'll have to deal with that later. ;)