Add dj.struct.leftOuterJoin
Allow AUTO_INCREMENT fields

* e.g. in primary key: 'prim_id  : int unsigned AUTO_INCREMENT   # ID'
* Leave fields empty when passing data to insert()
* Query the last assigned ID after insert() via dj.Relvar.lastInsertID
Fix typos and update URLs
Fix code style in dj.struct.leftOuterJoin
removed the option to delete the classdef files upon dropping a table
in responses to users' feedback.
Merge branch 'future' of github.com:datajoint/datajoint-matlab into future
bugfix related to autoincrement