Math plugin does not escape text hor html

[buehlefs]

The math plugin does not escape text for html (even if the renderer is configured to escape html).
This can be a problem when the math code contains html characters, e.g., \eft<1\right>.

Possible Fix:

# plugins/math.py
from ..util import escape

def render_block_math(renderer, text):
    if getattr(renderer, "_escape", False):
        text = escape(text)
    return '<div class="math">$$\n' + text + '\n$$</div>\n'


def render_inline_math(renderer, text):
    if getattr(renderer, "_escape", False):
        text = escape(text)
    return r'<span class="math">\(' + text + r'\)</span>'

But considering the output is always html, it could be a good idea to always escape the output.