Created a class in util called chunkbuffer that buffers reads from an iterator over strings (aka chunks). Also added to util (for future use) is a generator function that iterates over a file n bytes at a time. Lastly, localrepo was changed to use this new chunkbuffer class when reading changegroups form the local repository.

<item>
    <title>#desc|firstline|escape#</title>
    <link>#url#?cmd=file;file=#file#;filenode=#filenode#</link>
    <description><![CDATA[#desc|escape|addbreaks#]]></description>
    <author>#author|obfuscate#</author>
    <pubDate>#date|rfc822date#</pubDate>>
</item>