TEXT-126: Adding Sorensen-Dice similarity algorithm

[kinow]

Supersedes #103

The work in #103 seemed to be going in the right direction but needed some review before being merged. I started syncing the code and rebasing it, but noticed that the code had been done on master branch in a fork. However, that master branch was later overwritten by other commits for other pull requests.

This means I am not able to update the pull request (or at least I cannot think of a way of doing so), thus this new pull request with the same change (one commit with the same author, OP).

There were a few merge commits, which I rebased squashing everything into a single commit, keeping just the two files that were being displayed in the GitHub UI diff, and that contain the class and test for the Sorensen-Dice algo.

I will try to move it forward, even if the review comments are not displayed here. In case I do not managed to finish it, anyone is welcome to take it over. Just to make sure to read the feedback in the linked pull request, and address or comment CC'in others.

[garydgregory]

Please don't use assert-j ;-) it's not as clean as junit (assert-j makes a mess of trying to do assertEquals for example).

[kinow]

Please don't use assert-j ;-) it's not as clean as junit (assert-j makes a mess of trying to do assertEquals for example).

I hadn't seen that that was used in the test. IDE failed to compile, and then I simply rewrote that as normal JUnit + assertThrows. Not sure why that had been used before, but it's removed. Will send a few separated commits addressing different feedback, will wait for new feedback (if I manage to get it to some alright state), and squash or drop commits as needed 👍 Feel free to commit anything here if you'd like, at any time 👍

Thanks!

[kinow]

I think the CI build might pass this time. I fixed the git conflicts, then ide warnings, checkstyles, javadocs. For today that's all the time I had 🌧️ Going to continue another day, probably starting reading @aherbert 's comments like this one #103 (comment), which I think should be addressed before this is ready for a review & merge. Thanks!