tests/import: Add a test which uses ... in from-import statement.

tests/import/import_pkg7.py

+# This tests ... relative imports as used in pkg7
+import pkg7.subpkg1.subpkg2.mod3

tests/import/pkg7/__init__.py

+print("pkg __name__:", __name__)

tests/import/pkg7/mod1.py

+print('mod1')
+foo = 'mod1.foo'

tests/import/pkg7/mod2.py

+print('mod2')
+bar = 'mod2.bar'

tests/import/pkg7/subpkg1/__init__.py

+print("pkg __name__:", __name__)

tests/import/pkg7/subpkg1/subpkg2/__init__.py

+print("pkg __name__:", __name__)

tests/import/pkg7/subpkg1/subpkg2/mod3.py

+from ... import mod1
+from ...mod2 import bar
+print(mod1.foo)
+print(bar)