min -> max descirpoint
Added meaningful labels
Move code from notebook

Signed-off-by: Krzysztof Opasiak <ups100@tlen.pl>
Add implementation of suffix tre algorithm for document clusterin

Signed-off-by: Krzysztof Opasiak <ups100@tlen.pl>
 Add some tests to check tree build procedure

Signed-off-by: Krzysztof Opasiak <ups100@tlen.pl>