Render annotations in pandafium

v0.2.1

Merge pull request #16 from gradescope/ibrahim/ch25652/backport-annoa…

Update pdfium source to 2018-09-18

Merge pull request #9 from gradescope/ibrahim/2018-09-18

Update to build from 2018-09-18

Add --version flag

Shows the version based on the git tag.

First release

This is an early version that contains pdfium from 2016, when this repo was first forked.