pginstaller - pginst: Re-arrange contrib module checkboxes into 4

Log Message:
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Re-arrange contrib module checkboxes into 4 columns.
Add tooltips to checkboxes.

Modified Files:
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pginst/wxs:
dialogs.wxs (r1.31 -> r1.32)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/wxs/dialogs.wxs.diff?r1=1.31&r2=1.32)