Optional partial xml support

Nobody has claimed this yet.

It would be great if mini-html-parser can optionally parse XML text. For example:

``` javascript
str = "

• custom bold
• regular bold
";
a = htmlParser(str);
b = a.parse()[0];
b.childNodes[0].childNodes[0].childNodes[0].childNodes[0].nodeName
>> "X:B"
```

I guess the easiest way to do it is to add `':'` in `rstarttag` and `rendtag` regexps:

``` javascript
var rstarttag = /^<([-A-Za-z0-9_:]+) ... /;
var rendtag = /^<\/([-A-Za-z0-9_:]+) ... /;
```

Start by locating the parser code that defines the rstarttag and rendtag regular expressions. Confirm how optional XML parsing should be enabled, then verify that namespaced tags such as x:b can be parsed and produce the requested nodeName without changing ordinary HTML behavior.

Written by the indexing model from the issue text.