Fixing stack overflow when opening screenshare window

Update locales

Tested uploading of presentation.

 - download only tanslated locale strings (tx pull -a --mode=onlytranslated)

Fix focus chat message list key and label

[ HTML5 ] - Accessibility update 04

Improve the document conversion fallback logic by merging the pdf page extraction and image conversion using 'convert' to a single step page to image conversion using 'gs'. Anti-aliasing for text and shapes is also improved.

Make sure that blank swf is loaded if fallback document conversion does not work.

Fix poll options remain visible on html5, closes #3806 HTML5

Fixed user leave problem on private chat, close #3799 HTML5

HTML5: Switch to icons v11, update some icons in the client, minor UI touches

HTML5: Fix missing import causing breakouts to not work

 user internal userId instead of external userId 

Delete the initially converted swf to be sure that if fallback convertion does not work we get the blank swf loaded.

Fix user drop down - HTML5 Issue #3764

Fix multiple welcome messages, issue #3792 HTML5