fix buttons under android
Add isEmpty method to Stream, DecodeStream and ChunkedStream
Fix loading of fonts with empty font files (bug 866395 and issue 3522)
Add more unit tests for the API
Merge pull request #4812 from Snuffleupagus/more-api-unittests

Add more unit tests for the API
Merge pull request #4809 from Snuffleupagus/bug-866395-redux

Fix loading of fonts with empty font files (bug 866395 and issue 3522)
Merge pull request #4808 from fkaelberer/fixAndroidButtons

Fix strange looking buttons in mobile Firefox
Adds Promise to the getOperatorList
Terminate getOperationList and getTextContent every 20 ms
Merge pull request #4770 from yurydelendik/promise-operationlist

Adds Promises to getOperatorList