getDocumentPointsize: fix regexp

The previous regexp would match any number that was followed by either
"p" or "t" and use this as the document point size.  This led to

    \documentclass[a4paper]{artice}

being interpreted as a 4pt document.  As a result, plotted figures
wound up with grossly scaled font nodes (scale=3 or similar).

We instead want to only match digits at the beginning of a word,
followed by the string "pt".
only match digits+"pt" for point size
start an RStudio project
roxygenize
head() has been exported from utils, so :: instead of :::
let's use semantic versioning in DESCRIPTION, and get rid of this home-made strategy

http://yihui.name/en/2013/06/r-package-versioning/
starup message should appear in .onAttach() instead of .onLoad()

in the future we may do it, but for now, I just remove the startup messages
mv inst/doc to vignettes/
bump version, and clarify authorship/maintainership
ignore GNUmakefile
use grDevices:: to hide quartz() from R
when building vignettes, compress it
temporarily disable the vignette, since RForge does not have preview.sty at the moment
enable continuous integration via craigcitro/r-travis; really have to install LaTeX here
Merge pull request #1 from krlmlr/r-travis

enable continuous integration via craigcitro/r-travis
install pgf (tikz.sty is required for the tests)