[docs] Font quality in docs degraded in 3.6.3 in comparison to 3.6.2 -- please use type 1 fonts only

Example: tutorial.pdf

=> Documents are compiled with pdflatex -- can you ensure to use type 1 fonts and avoid the old type 3 fonts. The latex settings just needs a tuning and you get higher quality pdf docs.

All type 3 fonts can be replaced with type 1 fonts available in any TeX distribution.

It makes the documents more readable and enjoyable. -- Norbert