Datamatrix ECC200 16x48 with variable module size

[maxiride]

We have been using https://linux.die.net/man/1/dmtxwrite for a while but I'd like to use more this library.

I'm reading the code and fiddling around to implement a 16x48 datamatrix with a module size of 5 pixels but I have some questions related to a low knowledge of the datamatrix spec and I hoped to receive some feedback.

• What is the ECC Count? https://github.com/boombuler/barcode/blob/master/datamatrix/codesize.go#L8
• Does the encodeText() needs to be changed or is the encoding the same also for rectangular datamatrix?

I'd like to keep this ticket open for future questions and feedbacks as I learn the library and try to implement my changes, hopefully for a successful PR in the future.