Update r217 : Navigate between selected pins with Shift + arrow keys
Navigate between connected filters with Shift + left/right
Navigate between filters by direction with arrow keys
Draw selection markers on selected pins
Draw connection line arrow at centre of connection lines to make selection markers more visible on input pins
Highlight pin connection if either of connected pins selected
Removed cached current_filter, current_pin state in DisplayView and use currently selected pin or filter
Preserve selected pins and filters when filters refreshed
Fix context menu bug added in r324
Select newly inserted filters
Don't deselect pins after disconnection


git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@327 c2f33eb2-41b2-391d-4cb4-d9d0608729ba