Fixes intermittent rendering stop
Switch to threaded python server for tests.
fix for #2219, "provide a better error message when file= not found/accessible"

summary: create a new Exception class for missing PDF's, use it in place of generic

add new MissingPDFException to util.js
handle MissingPDF in api.js
handle MissingPDF in viewer.js, using new missing_file_error message
add new missing_file_error to l10n/en-US/viewer.properties
send MissingPDF from WorkerMessageHandler's loadDocument
send MissingPDF from GetDocRequest handler
Merge pull request #2626 from wfwalker/addmissingpdfexception

fix for #2219, "provide a better error message when file= not found/acce...
Merge pull request #2625 from brendandahl/threaded-server

Switch to threaded python server for tests.
Update zh-TW translation
Merge pull request #2631 from xavier114fch/zh-TW

Update zh-TW translation
Add Hankaku-Latin cid to Unicode mappings
Disable printing a selection for Firefox.
Add support for GBK-EUC-H encoding for cid fonts
Merge pull request #2633 from brendandahl/disable-print-selection

Disable printing a selection for Firefox.
changed the type1font cff wrapping to use offsets 391,392... instead of 0,1... for pointing to strings in the String INDEX
Merge pull request #2624 from vyv03354/bug835661

Add Hankaku-Latin cid to Unicode mappings
Merge pull request #2628 from mduan/issue2128

Add support for GBK-EUC-H encoding for cid fonts
Implement 9.6.6.4 of pdf spec for truetype fonts
Merge pull request #2606 from mduan/issue1512

For TTFs, implement section 9.6.6.4 from the PDF specs
Merge pull request #2634 from Pomax/type1-string-index-SIDs

changed the type1font cff wrapping to use offsets 391,392... instead of 0,1... for pointing to strings in the String INDEX
Merge pull request #2614 from yurydelendik/intermit-fullscreen

Fixes intermittent rendering stop