Complete syntax support for SageTeX

[shivangp76]

I read through the SageTeX documentation to make sure no commands were missed.

• A new in_sage() function was added.
• Bug fix: The texSagetexArg environment is now not considered a mathzone. This comes from the fact that $2+2=\sage{2+2}$ is a valid use of \sage (see SageTeX documentation). The contents of its argument should not be considered math, rather Python code.
• The \sage and \sagestr commands can be used in a mathzone and not in a mathzone, since their purpose is to just convert their Sage input into LaTeX output. Added support for this.

[lervag]

Thanks! I believe we should go forward with this, but I have a few comments.

[shivangp76]

Thanks for the feedback! I'm new to Vimscript, so I apologize for the poor code. I made the changes you requested. Let me know what you think.

[lervag]

Thanks for the feedback! I'm new to Vimscript, so I apologize for the poor code. I made the changes you requested. Let me know what you think.

No need to apologize! I'm very happy to see the contribution and I'm glad to see you not being too annoyed by my slightly pedantic review comments ;)

As you see, I had one more follow-up comment - I propose to not add the in_sage function at all. But I'm all ears if you want to argue it makes sense to add it.

[lervag]

Thanks; I've merged this now.