bump crengine: text typography by language

[poire-z]

Includes koreader/crengine#337 :

• Fix a few clang-tidy warnings
• Add support for <img src="data:image/png;base64,...>
• XML parsing: add more HTML5 named entities, optimize search
• Text: fix standalone BR not making an empty line
• Fix BR with "display: block" not making an empty line
• Fix hyphens from soft-hyphens not part of highlighted segments
• Use libunibreak for line breaking
• Adds TextLangMan for text typography by language

The added cre.getTextLangStatus() will allow us to get a feel of what languages have been seen and which hyph dicts loaded:

Noting a little thing that got me searching for a bug for quite some time:
The TextLangCfg tags we will see there are the ones that were actually seen by the code.
For a same book:

• on initial load or re-rendering: the full book content will be visited, so all the existing lang= attributes tags will appear here
• after exit and load from cache, this list will be smaller, and lang= attributes tags will appear here only when they are met: when you turn pages and meet new sections of the book that are to be rendered and drawn.

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This change is 

[poire-z]

@Frenzie: are you fine if I bump this into frontend later this afternoon?
Is your tag v2020.04.1 enough for you to get binaries to add to the release?

[poire-z]

And btw, didn't you need this month to do as [i18n] Bump translations submodule for v2020.03 release last month?

[Frenzie]

You're right, I forgot that. It doesn't matter for the resulting builds; it's just a matter of syncing up translations with the code if you should want to check out that tag in the future.