Merge pull request #35 from laurentpayot/master

Patch for issue #34 (ListFields not present in a DocumentForm are deleted after the form saving)
Minor changes
EmbeddedDocumentForm optimization with position argument and atomic updates
Merge pull request #36 from laurentpayot/EmbeddedDocumentForm-optimization

EmbeddedDocumentForm optimization: position argument and atomic updates
Load instance in EmbeddedDocumentForm.__init__ if position argument is provided
Test for parent_embedded_field before using it
Updated documentation for embedded fields
More docs
And again doc formatting
Figure out position if instance is provided for embedded forms
actually assign position and not just figure it out. Dough!
Use position argument in embedded formsets
A couple small fixes and some code formatting
Initial support for MapFields. Probably full of bugs and not too sure about the HTML
Added a field map to the generator to handle fields like SortedListField