Add conversion & unit tests for dgT, dtT & dsTMatrix

[binxiangni]

In order to solve #17 and #114.

[eddelbuettel]

Wait, there seem to some of the same commits in both pull requests. That's generally not a great idea.

[binxiangni]

Maybe I should first close this PR.

[eddelbuettel]

I now merged #135. If we're careful we could probably open this and merge it too.

We can either open, and merge (maybe simplest) or cherry pick the last two commits.

In general, let's try to only work on one open PR at a time. I'm sorry I took four days on the last one but review is useful.

[eddelbuettel]

There is however a conflict now so that would have to be resolved first.

[coatless]

Might I suggest for this PR that @eddelbuettel uses a merge squash? In essence, the working history of the branch is condensed into one commit that is added into the master. This keeps all of the changes of the PR together without adding the duplicate history from the previous PR back into the master.

Merge and squash via:

• GH's PR interface
• CLI git

git checkout master
git merge --squash branch_here
git commit

[eddelbuettel]

Yes. I already used a merge squash on the last one. Trivial from GitHub's GUI.

[coatless]

Missed that. Awesome!

[eddelbuettel]

No worries, and thanks for the CLI reminder. Noted, and copied to local README.

[eddelbuettel]

Tests find on my end in a branch, so in it goes. Hurray :)