mime: tests and examples.

mime: tests and examples.

Additional mime-specific tests.
Existing tests updated to reflect small differences (Expect: 100-continue,
data size change due to empty lines, etc).
Option -F headers= keyword added to tests.
test1135 disabled until the entry point order change is resolved.
New example smtp-mime.
Examples postit2 and multi-post converted from form API to mime API.