* Support more scripts in \text{} environments.
This diff is a follow-up to PR #1060 which added support for Indic scripts.
In order to support Czech, Turkish and Hungarian text (at least) inside
\text{} environments, we need to recognize the Latin Extended A and B
Unicode blocks. The patch also adds support for Georgian, and enhances
support for Cyrillic by defining the entire Cyrillic unicode block instead
of defining symbols for a subset of Cyrillic letters as we did previously.
* Only return fontMetrics for supported Unicode scripts in text mode
The Unicode scripts listed in unicodeScripts.js are supported in text mode
but getCharacterMetrics() was returning fake metrics for them even in
math mode. This caused bad handling of \boldsymbol\imath
* use Mode from types.js
This patch just makes KaTeX recognize Unicode codepoints in the
range \u0900-\u109f so that those South and Southeast Asian scripts
do not get automatically rejected.
The patch also generalizes the way that Unicode blocks are handled
to make it easier to add support for new scripts in the future.
src/unicodeRegexes.js is replaced with the new file src/unicodeScripts.js
