Allow multiple config files in joinsysdef.pl. Support ignoring items by namespace on the command line in sysmodelgen
<SystemDefinition schema="3.0.0" xmlns:qt="http://www.nokia.com/qt">
<package id="search" name="Search Apps" levels="eng base app api">
<collection id="search_info" name="Search Info">
<component id="search_build" name="Search Build" introduced="^4">
<unit bldFile="group"/>
</component>
</collection>
<collection id="searchui" name="Search UI">
<component id="searchui_build" name="Search UI Build" introduced="^4">
<unit bldFile="searchui" qt:proFile="searchui.pro"/>
</component>
</collection>
</package>
</SystemDefinition>