#25 Add option to get image id as variable

[Felipe Leme]

I have a page where I need to get the id of the image
generated by the img tag. I thought that should be
already a way to get that, but I didn't find out how,
so I created a patch sets a variable with that info.
For instance:

<cewolf:img chartid="pie" renderer="graphics"
width="378" height="170" imageIdExport="imgId"/>

Will create a scripting variable (i.e., a bean of the
java.lang.String class and page scope) containing the
id of the image (as returned by the storage provider).

The patch includes change to the ChartImgTag and the
TLD as well - notice that this patch already assumes
cewolf.tld is located at the META-INF/tlds directory.

[Felipe Leme]

SVN patch