Single Table Inheritance scratch (not fully working yet)
Updated README to reflect possibility of adding fields in subclasses.
Fixed problem with accessing all field values in subclasses.
Removed dynamic calculation of version number.

This is because it may lead to import problems in virtualenv.
Fixed class changing in model initialisation.
Added basic relational fields support.
Moved tests to typedmodels package.
Moved tests to typedmodels package.
Fixed ordering by type in test comparisons.
Merge branch 'new_branch_name'
Tests for fields in subclasses.
Added known issues to README.
Changed Python testing version number in README.
Fixed problem with uncontrolled expansion of fields from subclasses.
Fixed problem with field ordering in model constructor.
Added info about relative imports to README
Updated info about relative imports.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	README.rst
Added Emacs backup files to .gitignore.
Better generation of related names for related fields.