The module type constant for content-type modules is MODULE_TYPES.
array(string|int) type_from_extension(string ext)
Return an array ({ content_type, content_encoding })
devised from the file extension 'ext'. When 'ext' equals "default",
Roxen wants to know a default type/encoding. If the content-type
returned is the string "strip", the content-encoding returned
will be kept, and another call be made for the last-but-one file
extension to get the content type (eg for ".tar.gz" to
resolve correctly).
