Fix problem with sbs config xml parsing. Make sure to trim error message to avoid erroneously adding an error when there is none. Fix problem with adding system includes for variants.
<contexts>
<context id="viewer" title="Sample View">
<description>This is the context help for the sample view with a table viewer. It was generated by a PDE template.</description>
<topic href="/PLUGINS_ROOT/org.eclipse.platform.doc.isv/guide/ua_help_context.htm" label="Context-sensitive help">
<enablement>
<with variable="platform">
<test property="org.eclipse.core.runtime.isBundleInstalled" args="org.eclipse.platform.doc.isv"/>
</with>
</enablement>
</topic>
</context>
</contexts>