Allow use of any online ditaa service

[mithat]

With ditaa.org being down and no Java on my shared hosting, I am no longer able to use this plugin--and I suspect others are in the same position. One solution might be to allow the user to use any remote ditaa service--though I have no idea if any others exist or what's involved in setting one up.

[splitbrain]

Unfortunately I don't know any.

[mithat]

If you can build in the ability to use other ditaa providers, I will look into what's required to set up your own service.

[mithat]

The following might be helpful: https://github.com/athoune/Ditaa-web/