use ../bin/knit to avoid relying on knit to be on the PATH
add README for knitr-graphics dependencies. Fixes #650.
fix path in README
Merge pull request #652 from krlmlr/knit-bin

use ../bin/knit to avoid relying on knit to be on the PATH
I remember Github simply supports links to files using relative links
inst/bin/knit is just an R script, so we can make this portable in other OS'es as well
bump version
prettify output of print_knitlog

- fix output if only one message is printed
- remove extra newlines
new util function try_silent
Merge pull request #653 from krlmlr/silent-inline-errors-prep

refactorings