[LaTeX] Added support for inline math ($...$) in a single line

[r-stein]

This has been requested in #61 and adds support for latex inline math ($...$) in as single line:

Multi line support would be way more complicated, since we cannot easily see if we are inside a math block.

[excetara2]

Just letting you know this does not work as I would expect it to for many examples I have tried. If you put the cursor in front of the 5 it will just highlight 5$ and not highlight the whole $...$. Also another command you can try is $550\Hz$ or $220\alpha$. Both of these if the cursor is on either the number side or command side it only selects the left or right part (eg. $550) and won't select the whole $....$.

[r-stein]

@excetara2 Yes currently the $ is used as a word character because it is used for variable names in some programming languages. Hence we should use different word character. I have already prepared something for this, but I have still minor struggles with the resulting behavior. However I will update it soon, since it's better than the current one anyway =)

[excetara2]

@r-stein Yeah I've given it a try and seems a lot better. At least everywhere I tried it seemed to eventually select inside the '$' albeit a bit slowly depending where the cursor was but definitely much better than the previous implementation.