Add adp extension (as in AOLserver Dynamic Pages) to the text/html section.
Merge remote-tracking branch 'upstream/develop' into mmext
Use AbstractFile.getNameExtension()
Also add "adp" extension to plaintext.
Get the same extension that Mismatch module uses.
safety dance
Merge pull request #433 from SynapticNulship/mmext

Changes to use AbstractFile.getNameExtension()