Introducing the Inference package

[danyaljj]

Changes

• Adds inference package as a module: Addresses #53
• Moves Gurobi solver to the inference module (and removes ojAlgo, since it already existed in inference package).
• Removes the datastructures moves to core-utils and uses core-utils as dependency

[danyaljj]

So apparently the thing we discussed in #77 doesn't work and Semaphore fails.

src/main/java/edu/illinois/cs/cogcomp/lbjava/frontend/GenerateParserAndSymbols.java:18: error: package java_cup does not exist
import java_cup.Main;
src/main/java/edu/illinois/cs/cogcomp/lbjava/frontend/GenerateParserAndSymbols.java:45: error: cannot find symbol
               ^
            Main.main(javaCupArgs);
            ^
  symbol:   variable Main
2 errors
  location: class GenerateParserAndSymbols

I don't see any alternative other than having the inference package in another repository :-/ Any opinions/suggestions?

[christos-c]

We already have a separate inference package: https://gitlab-beta.engr.illinois.edu/cogcomp/inference