added a try catch exception when trying to get branch support from phyloxml tree
add support for sp_naming function in evoltrees
merged with 2.2
cleanned and updated doc
Merge pull request #72 from fransua/2.2

2.2
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.