Instances of this class map file extensions to MIME content types based on a
default MIME table.
The default values can be overridden by modifying the contents of the file
"content-types.properties".
Constructs a MIME table using the default values defined in this class.
It then augments this table by reading pairs of extensions and
corresponding content types from the file "content-types.properties",
which is represented in standard java.util.Properties.load(...) format.
Determines the MIME type for the given filename.
Parameters: filename - The file whose extension will be mapped. The mime type associated with the file's extension or null if nomapping is known.
