Checkout of PGFplots 'stable' branch'

Performed with
git archive --format=tar --remote=git://pgfplots.git.sourceforge.net/gitroot/pgfplots/pgfplots stable | tar -xf -
per http://stackoverflow.com/a/353830
More Joint Program graphics and LyX BibLaTeX module
Pre-merge commit with several changes

modified:   beamerthemeCECP.sty
 - Move the layer declaration to fix output

new file:   jp/logo-vertical.pdf
new file:   pixel.png
 - More graphics

deleted:    mf/.gitignore
deleted:    mf/README
 - Local (k-laptop) version had an empty directory mf; will merge
   k-desktop version which has latest PGFPlots incuded in the working
   tree in this directory. Purge current stuff in preparation
Merge branch 'master' of ssh://k-desktop/~/vc/tex