Should we consider having travis build the full html docs including the pdf version? This is now pdf + 100 dpi png and not 80 dpf + 200 dpi png + pdf? It would be nice to have that in the devdocs.

A local benchmark shows that this increases the build time by about 2 min.

real    6m39.623s
user    6m20.541s
sys 0m9.313s

vs

real    4m55.762s
user    4m43.091s
sys 0m6.432s

Alternatively we could special case on the master branch and only build the pdf versions of the figures when we build directly from master not from PRs but that seems more confusing than it's worth?