Use Nemeth Indicators to Delimit Math Content in Text

## MathCAT Version

MathCAT-0.6.6 (NVDA Add-On)

## Current Behavior

When MathCAT encounters in-line math content and is set to render math as Nemeth, it inserts one space before the math and two spaces afterward to distinguish it from the surrounding text.

## Proposed Change

[Nemeth indicators](https://nemeth.aphtech.org/lesson3.8) would likely serve as better delimiters. Benefits include

+ a more natural rendering of mixed content (text interspersed with math), since that is how such content would be brailled physically.
+ more conspicuous indication of code switching (especially useful in STEM documents).
+ easier identification of symbols (e.g., punctuation) directly following math content, as the Nemeth indicators occupy the full height of the cells they use.
+ the ability (at least in theory) to use NVDA's braille output as (nearly) embosser-ready Unicode braille (since the standard is to use Nemeth indicators in UEB documents with Nemeth math content).

Perhaps an option could be given to toggle this behavior if desired.

## Comparison

### Mixed-Content Statement

In this case, $y$ is proportional to $x^2$.

### Current Nemeth Output (Unicode)

⠠⠔⠀⠹⠀⠉⠁⠎⠑⠂⠀⠀⠰⠽⠀⠀⠀⠊⠎⠀⠏⠗⠕⠏⠕⠗⠰⠝⠁⠇⠀⠞⠕⠀⠀⠭⠘⠆⠀⠀⠲

### Proposed Nemeth Output (Unicode)

⠠⠔⠀⠹⠀⠉⠁⠎⠑⠂⠀⠸⠩⠀⠽⠀⠸⠱⠀⠊⠎⠀⠏⠗⠕⠏⠕⠗⠰⠝⠁⠇⠀⠞⠕⠀⠸⠩⠀⠭⠘⠆⠀⠸⠱⠲

If Nemeth indicators were adopted, then the grade 1 symbol indicator would not be necessary before the $y$.