Stripping _ from property tags & breaking multi-line comments

[rrshaban]

Hi, I've two issues that came up while trying to use go/htfloml for a fontconfig file (XML). I imagine that is running the latest version of this code.

Inputting

<include ignore_missing="no">local.conf</include> returns
<include ignore missing="no">local.conf</include>.

Note the disappearing underscore from ignore_missing.

Second,

Inputting

<!--
  something
  <foo>. bar
  more
-->

returns:

<foo>
  . bar more -->