Merge pull request #19 from dantleech/fix

Fixed wrong method name
Added documentation for preMove and postMove events
More explanation about move events
Add note and change the section name
Merge pull request #20 from laupiFrpar/move-events

Added documentation for preMove and postMove events
cleanup event documentation
update associations documentation
cleaning up docs
cleanup link and list
Merge pull request #21 from doctrine/update-associations-doc

update associations documentation
Added some info about the nullable attribute
Merge pull request #22 from wjzijderveld/nullable-annotation-info

Added some info about the nullable attribute
Fixed attribute names