Parses an XML-file specifying the 'annotations'.
The XML must have the structure:
<args>
<option field="" method="" name="" usage="" metavar="" handler=""/>
<argument field="" method="" usage="" metavar="" handler=""/>
</args>
Exactly one of the attributes 'field' or 'method' must be set.
The 'handler' value specifies a full qualified class name.
Example
<args>
<option field="recursive" name="-r" usage="recursively run something"/>
<option field="out" name="-o" usage="output to this file" metavar="OUTPUT"/>
<option method="setStr(String)" name="-str"/>
<option field="data" name="-custom" handler="org.kohsuke.args4j.spi.BooleanOptionHandler" usage="boolean value for checking the custom handler"/>
<argument field="arguments"/>
<args>