fix problem with layout function validation and fixes examples
removed buggy and cryptic evoltree webplugin example
repaired very didactic example "measuring_evolution_trees". Anti-python cosmetic changes.
Merge pull request #73 from fransua/master

repaired very didactic example "measuring_evolution_trees". Anti-python cosmetic changes.
more clear new_seq_face.py example
re-fixes phyxmltree problems with support and dist attributes.