Auto close for checked components

This is a proposed fix for
https://github.com/dblock/dotnetinstaller/issues/18
After installation, only the components that were checked (selected for install) are examined. If they are installed, the installer closes (if auto_close_if_installed is set). 
That is, if all items that user had requested to install are successfully installed then auto close. If some of selected failed, let the user to examine the current state of installation. Items that were not selected for installation are ignored in this check.

I'll add corresponding tests if this fix will be found appropriate.