Building tensorflow via make is deprecated

[Mojken]

Hello, I ran into an issue building this when it tries to build TFLite, so I opened an issue about it. Turns out, building with make is deprecated, and since your project can't be built because of this, you need to update as per their instructions.

[bkirwi]

Yeah, this is largely not upstream tensorflow's fault. The bottleneck at the moment is the tflite library I'm using, which is unmaintained and stuck on a very old version of the tensorflow project.

If I were to rework this today I would rewrite this code to use tflitec: it seems better-maintained, and relying on the C dynlib is I think a more pragmatic approach to avoid the build hell. I am unlikely to find time to do this in the near term, but I would certainly accept a PR with a tensorflow upgrade.

In case you're not interested in the handwriting recognition and trying to build the project for its other features, note that you can build with --no-default-features and avoid the trouble.