I think it would be nice to have the option to dump a raw graphviz DOT file instead of the sppf.png for a few reasons:

• the file size is a lot smaller
• it's nice to be able to "do things" with the resulting tree in its structured form, rather than navigate the rendered bitmap
• it's only one extra (or no extra) line and could be optional, e.g. if you've turned on "debug" mode.

Any though

The rust code in the .lalrpop files are still on rust 2015 and need to be manually updated since cargo fix won't work on those files.

We should also update the generated code to emit 2018 idiomatic code (see #2018 )

I'm using link-grammar-5.3.15.

This one didn't work for me:
https://github.com/opencog/link-grammar/blob/master/bindings/java/org/linkgrammar/LinkGrammar.java#L43
Even when I added /usr/local/lib to jvm props:

java.lang.UnsatisfiedLinkError: no liblink-grammar in java.library.path

I fixed it by replacing that line into:

System.load("/usr/local/lib/liblink-grammar-java.so")