I just use the normal R CMD build/check, but I'm okay if devtools is preferred
fixed a bug related to multiple expressions on the same line, reported by Bill Venables

the real change is from `if (!is.null(call))` to `for (expr in call)`; the rest of changes are basically further indenting the code
closes #42: append \n to all comment lines except the last line when the whole block of code only consists of comments
clean up the old tricks to get rid of Rplots.pdf after #44
merge the test from test-graphics-nofile.r to test-graphics.r after #44
bump version