[PATCH] Useless messages for exception thrown in Image codec

PropertyUtil references a non-existent resource bundle: "org.apache.xmlgraphics.image.codec.resources.Messages".

The PropertyUtil class is used to generated localized message for the exception thrown in image.codec subpackages, and since the resource is not supplied, the generated exceptions messages are all useless (e.g. "PNGEncodeParam0").

I propose to change the pattern of the message key, instead of using "classname + number", by using a "real" meaningful message, like "invalid value supplied".

I will attach shortly:

• A patch to PropertyUtil to be able to give arguments to the messages,
• an enhancement of the messages for some classes in image.codec,
• a resource bundle (for Locale "en" and "fr")