Added ggally_histogramDiag.R
Merge branch 'master' of git://github.com/muschellij2/ggally into muschellij2-master
Merge branch 'dev' into muschellij2-master

* dev: (32 commits)
  git merge fix.  namespace now fixed
  no double import of ggplot2
  added backslash to work with new roxygen
  added news about removing ggsurv
  removed namespace of plyr::ddply.  already imported in general plyr
  fixed news
  updated news and description
  documented
  worked on imports of plyr, ggplot2, and reshape
  shortened ggnet example time
  removed "ggplot2::" from functions
  added id as global var in ggnet
  removed require to ggplot2 as it is 'depend'ed
  added ..Rcheck to ignore
  added ggplot2 import for depends
  stored the last pl.kid to have the labels attach nicely, like it was originalll
  documented
  added edwin to the authors
  passes check() and documents().  changed example to use coord_cartesian and not xlim to preserve exiting lines.
  added small comment for helper functions
  ...
updated the barDiag function to scale for continuous variables.