Added shortintertext as text context.

[senesc]

Currently the content of \shortintertext{} is consideted math context by the plugin. With this PR I added shortintertext to the "Text Inside Math regions" patterns.

[lervag]

Can you provide a minimal example document that is relevant here?

[senesc]

Sure!

\documentclass{article}
\usepackage{amsmath}
\usepackage{mathtools}

\begin{document}
\begin{gather*}
	e^{i \pi} + 1 = 0
	\shortintertext{This is an example of shortintertext}
	e^{i \pi} + 1 = 0
\end{gather*}
\end{document}

[lervag]

Cool, thanks. Now, \shortintertext is a command from the mathtools package, so we should not define this in core.vim. Instead, we need to update this file:

https://github.com/lervag/vimtex/blob/master/autoload/vimtex/syntax/p/mathtools.vim

In addition, I would kindly ask that you update the corresponding test file with a minimal example (just add an equation with the relevant command):

https://github.com/lervag/vimtex/blob/master/test/test-syntax/test-mathtools.tex

[senesc]

Thanks for your input! I updated the correct file and added an example to the test folder. Hope everything is okay now

[lervag]

Thanks; I've merged (and then applied some minor adjustments).