Fenced block syntax for mathematical expressions

Users can now delineate mathematical expressions using ```math fenced code block syntax in addition to the already supported delimiters. Two dollar sign $$ delimiters are not required if this method is used.

**Here is some math!**

```math
\sqrt{3}
```

**Here is some math!**

```math
\sqrt{3}
```

becomes

Read more about working with advanced formatting