Fix Valley issues

Fixes some of the complaints @jhoff had about valley. 

1. New enemy behaviors for the mariachi band.
They now follow you around if you've damaged them beforehand, and if you're in a certain range. Trombonists don't have any special abilities, but violinists have a 'dash' attack and charges at the player, and guitarists have a 'push' attack that send the player flying back.
2. Add a scene node at the end of valley 3 before the fence to suggest to the players that they should talk to the fencekeeper
3. Make the unusually large shrub even unusually larger