Create an ability to have empty vectors
Remove old task
Rearrange clusters into a chain

(I've not tested in yet)
A few bugs fixed.
Nothing much
Convert SmartFile implicitly from String and to File
Remove empty initialization term from enumeration of clusters
Dump both of cluster sets by default.
Discard pairs of the same vectors before clustering procedure 

... to preliminary resolve a freezing problem.
Cleanup the code
Clean up the code
Support chains of clusters
:(
Add an ability to cache object with serialization()
Cache aligned tree
Make tree and vector Serializable
Filter duplicated items to avoid fails
Mark directories with keyword
Merge remote-tracking branch 'origin/cluster_with_chains'

Conflicts:
	src/ru/wordmetrix/webcrawler/SmartFile.scala
	src/ru/wordmetrix/webcrawler/TreeApproximator.scala
	test/test/ArrangeText.scala
	test/test/Draw2DMap.scala