Add markers for embedded objects.

This partially fixes issue #92.

In click-to-play mode, <embed> objects can be activated via context menu: Alt, c.
Merge pull request #109 from mozillazg/develop

Update Simplified Chinese translation
Merge pull request #94 from LordJZ/develop-embed

Add markers for embedded objects.
Closes #110. Use default hint chars if custom hint chars string is empty
Closes #111. Validating custom hint characters.
If there are less than 3 custom hint characters the the default hint characters are used.
Custom hint characters are filtered to remove duplicates.
Bumped version to 0.4.7 and updated changelogs
Merge branch 'release-0.4.7' into develop
Reversed change log order
Closes #117. Hotfix for custom hint chars
Version bump and changedlog update
Merge branch 'release-0.4.8' into develop
Merge pull request #2 from akhodakivskiy/develop

sync with master repository