- basic support for parsing BIFF2-4
- basic support for writing BIFF2
- cleaned up some bad substr uses for IE6 compatibility
- added flow type annotations for xlsx.flow.js
- added numerous null guards (fixes #255 h/t @martinheidegger)
- README cleanup (fixes #539 h/t @oliversalzburg)
- pin jszip to local version (closes #408 h/t @limouri)

bower issues:

|  id  | author            | comment                                   |
|-----:|:------------------|:------------------------------------------|
| #254 | @kkirsche         | fixes #254 by removing version from json  |
| #165 | @vincentcialdella | fixes #165 by changing default script     |
| #180 | @owencraig        | fixes #180 by using xlsx.core.min.js      |

format issues:

|  id  | author            | comment                                   |
|-----:|:------------------|:------------------------------------------|
| #271 | @morstaine        | fixes #271 by reworking related parse fns |
| #504 | @JanSchuermannPH  | fixes #504 detect FullPaths h/t @Mithgol  |
| #508 | @basma-emad       | fixes #508 offending file used `x:` NS    |