plain tex's mplibcode too is now local
begingroup/endgroup is better than bgroup/egroup
more robust btex ... etex parsing
making doc needs lualatex not pdflatex
mpfun seems to be a typo
add some more test figs
do not ignore 'withcolor' option
recognize withcolor option for normal text as well
Merge pull request #9 from dohyunkim/master

support 'withcolor' option