Indices - add index to get labels on the tree

[GoogleCodeExporter]

it would be useful to be able to get the set of labels that exist on a tree.  
When used as a pre_calc this will simplify some of the calculations as they 
won;t need to check for existence.  

A pre_calc_global could be to identify all the labels that are not on the tree, 
and use these to delete such labels from the various label_hashes.  

Original issue reported on code.google.com by shawnlaffan on 9 Aug 2012 at 1:08

[GoogleCodeExporter]

This issue was updated by revision r1069.

Add methods to get nodes not in the tree (to be called as a pre_calc_global), 
and also those that are (called as a pre_calc).

Original comment by shawnlaffan on 9 Aug 2012 at 1:10

• Added labels: ****
• Removed labels: ****

[GoogleCodeExporter]

Original comment by shawnlaffan on 9 Aug 2012 at 3:16

• Changed state: Started
• Added labels: ****
• Removed labels: ****

[GoogleCodeExporter]

This issue was updated by revision r1309.

Add indices to give the number and proportion of labels not on the tree.

Original comment by shawnlaffan on 30 Oct 2012 at 4:00

• Added labels: ****
• Removed labels: ****

[GoogleCodeExporter]

This issue was updated by revision r1312.

Make the index work properly.  

Original comment by shawnlaffan on 30 Oct 2012 at 4:19

• Added labels: ****
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[GoogleCodeExporter]

Mark as fixed.  

Original comment by shawnlaffan on 28 May 2013 at 4:45

• Changed state: Fixed
• Added labels: ****
• Removed labels: ****