Revert remove_small_objects to raise TypeError
Merge pull request #460 from jni/raise-type

BUG: Revert `remove_small_objects` to raise TypeError.
Change deprecated decorator to display warning in doc string
Remove duplicate code for alternative function
Use double instead of single quotes for doc string
Make deprecation warning in doc string bold
Merge pull request #462 from ahojnnes/deprecated-doc-string

DOC: Change deprecated decorator to display warning in doc string.
fix comment
DOC: minor fix ellipse_perim.