Fix ranging issue, update to unicode 14.0.0

[bartwe]

Fix issues with string length ranges being put into int and unsigned instead of kept in size_t. Fix issue with int typed functions returning char typed values which are assigned to char typed results. Update data to unicode 14.0.0

[adah1972]

First, I would like to thank you for the enhancement efforts.

For details:

• Regarding 246f3ff, overall fine. Would you please take a look at the make check failure too? I can take a look later, but it takes time.
• Regarding ab4665a, performance degradation could be a concern. Is unsigned good enough? (Even this is arguably unnecessary, as the array involved is statically bounded, and the size should be fine. But the change is fine apart from the potential performance loss on 64-bit systems.)
• Regarding 0573f44:
  • ends_with change might affect performance
  • lb_process_next_char change is API-breaking: is it really worthwhile?

It might also be a good idea that you break these PRs so that I can accept them separately.

[bartwe]

Closing and splitting into separate prs