String truncation: try to avoid scanning if obviously in range.
Column.maxCharacterWidth.
SUBSTRING.
Add a YAML test for that.
Tweak some tests.
Don't assume charset name has been normalized here.
Bump the DATA_VERSION. Fix the check for DATA_VERSION.
merge MMcM: Fix issues with codepoints >= U+10000

Merge pull request #1049 from MMcM/sql-layer/varchar-unicode-surrogates
https://github.com/FoundationDB/sql-layer/pull/1049