20 chrome

* Make it working with the navigator chrome
* The main modifications concern the file download. It is now performed via the `URI` scheme instead of `IFRAME`.
* This introduces non backward compatibility since the signature of the method `App.buildURI`, `App.save` and `App.saveAs` have changed. In addition, `pdf` and `png` files has to be encoded as `base64` string on the server side.
* There are new properties `App.extToURI`, `WithUrlSelector.defaultURI` and `pGridExport.fileroot`.
* The current implementation is working for firefox and chrome.
* Close #20

See merge request !16

Add the helper function inline_alert.

* Close #18

See merge request !14

Add the version for the matplotlib and pandas libraries.

* Close #17

See merge request !13