Update issue #170 : added tooltip content for pins, connection lines (Media sub type and format block details) and filters (registry name and file name if any).
REMAINING BUG : Tooltip itself stops working after click until view exited - this bug seems to be present in the CodeProject sample code too.
REMAINING BUG : If no text to display a rudimentary part-tip is displayed - any way of not drawing if no text is available?
Tooltip delay time decreased for faster feedback
Tooltip now operates via abstract callback so will work in multiple graph windows and can be re-used elsewhere
Increased selection margins and centralized value in Filter::SELECTION_BORDER
Format block parsing code moved to DSUtil::FormatBlockSummary.


git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@250 c2f33eb2-41b2-391d-4cb4-d9d0608729ba