Handle < and > in array column specifiers

I just discovered the next issue when array's is used instead of case.

The test case:
```
\documentclass{scrartcl}

\usepackage{amsmath}
\usepackage{array}

\begin{document}

\setlength{\arraycolsep}{1pt}
\begin{equation}
x =
\left\{ \begin{array}{>{\arraybackslash$} p{3cm} <{$} l}
y - 1, & \mbox{if } 1 \\
y, & \mbox{if } 2 \\
\end{array} \right.
\end{equation}

\end{document}
```

Error:
```
[WARNING] Could not convert TeX math 'x =
\left\{ \begin{array}{>{\arraybackslash$} p{3cm} <{$} l}
y - 1, & \mbox{if } 1 \\
y, & \mbox{if } 2 \\
\end{array} \right.', rendering as TeX:
ft\{ \begin{array}{>{\arraybackslash$} p
^
unexpected ">"
expecting white space, letter, "|" or "}"
```