RFR 8154483: update IGV with improvements from Graal

[Tom Rodriguez]

http://cr.openjdk.java.net/~never/8154483/webrev

This is a collection of small improvements to IGV developed while working on Graal.  I’ve categorized them below

Bug fixes:
  Reset folder in top component to release reference to old graphs 
  Fix concurrent modification exception in IGV 
  Fix HTML quoting in tooltips and remove useless entries from search box 

UI improvements:
  Fixed keybinding for open and save actions in IGV 
  Allow importing multiple files at once in IGV 
  Make node searches look through the graph history for a match 

Performance related improvements:
  Add info message about time spent parsing files 
  Relax expensive assert in IGV 
  Reduce overhead of hash computation for graph identity checks 
  Increase Integer cache size in IGV 
  Share properties in IGV 

Binary graph format:
  Add folder and graph property support to binary graphs in IGV 
  Handle Strings larger than buffer size properly in IGV