Add separator and field options to ManyToManyWidget
Merge pull request #107 from bmihelac/ManyToManyWidget-optional-separator-and-field

Add separator and field options to ManyToManyWidget
Preparing release 0.2.3
Back to development: 0.2.4
Fix error message when linking through a non-relation field.

When a ModelResource's `fields` include something that looks like a model
relation (such as `model__field`), but `model` is a plain field instead of
a relation, we used to crash with an error message that did nothing to
identify the bad field specification. This patch improves the error message
on failure.
Fix deprecation warning
Improve error message when fields don't match dataset.

Currently if you upload a file that doesn't include a required column, you
just get an error like "KeyError: 'id'". This patch improves the error message
so that the problem is easier to understand and solve.
Merge pull request #108 from aptivate/fix_link_to_nonrelation_field_error_message

Fix error message when linking through a non-relation field.
Commit a blind fix for Python 3.3 errors.

https://travis-ci.org/bmihelac/django-import-export/jobs/28887412
Allow ModelResources to modify field settings during/after construction.

Allows a ModelResource to change its column names systematically, based on the
Django Field's verbose name, for example.
Merge pull request #110 from aptivate/allow_override_resource_field_construction

Allow ModelResources to modify field settings during/after construction.
Another blind fix for python 2/3 issues.
Improve error message when Resource names a nonexistent field.

When someone creates a Resource referencing a field that doesn't exist
via a ForeignKey:

	class BrokenBook(resources.ModelResource):
	    class Meta:
	        model = Book
	        fields = ('author__nonexistent',)

We replace the standard Django error message:

	FieldDoesNotExist: Author has no field named u'nonexistent'

With a message that shows the path to the field that didn't exist (and leaves
out the spurious "u"):

	FieldDoesNotExist: Book.author.nonexistent: Author has no field named 'nonexistent'
Fix Python 3 by not mixing unicode and byte strings.
Merge pull request #112 from aptivate/fix_link_to_nonexistent_field_error_message

Improve error message when Resource names a nonexistent field.
Merge pull request #109 from aptivate/fix_missing_field_error_message

Improve error message when fields don't match dataset.
Add column name to ValueError from Field.clean()

It's useful to know which column failed to validate, and not always obvious.
This change adds the column name to the ValueError message, for example:

	Column 'id': invalid literal for int() with base 10: 'foo'
Merge pull request #113 from aptivate/add_column_name_to_clean_error_message

Add column name to ValueError from Field.clean()
Properly handle import/export of NullBooleanField
Updated changelog and added Andrea Cimino in authors file