moved models/ stuff under DataMapper folder. served for many testings.
removed test.csv, and use csv in DataMapper/models/friends.csv.
test Entity classes.
fixed getting short model name; strrpos...
model name will NOT start with \ (backslash).
addeda comment.
more test on Entity.
removed _ from all public method; changed name as well; added set methods.
added tests on {get|set}{Entity|Property}Attribute.
test on array access.