Update mint branch to be compatible with euclid master

[icefoxen]

Also updates mint to 0.5.1. The only real difference is changing Frommint::RowMatrix2x3 for TypedTransform2D to Frommint::RowMatrix3x2. This may or may not be 100% valid since my understanding of the math and how it all fits together isn't GREAT, but...

Should supercede #205

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This change is 

[kvark]

LGTM, thanks for reviving this!
It would be good to rebase this instead of adding a merge commit.

[kvark]

the ^ here shouldn't be necessary

[nical]

LGTM

[kvark]

@icefoxen ping about rebasing and nits

[icefoxen]

@kvark shoot, slipped my mind. I'll get it done Hopefully Soon.

[icefoxen]

Rebased in #303 . I can try to push it to this branch if you want?

[kvark]

@icefoxen yeah, I don't think it makes sense to file a new PR just for the rebase.

[icefoxen]

done

[kvark]

@icefoxen there shouldn't be any rebase merge commits. Ideally, just a single fix commit after my original ones. Could you rebase some more please?

[icefoxen]

No. I'm sick of this song and dance and did exactly what you wanted me to: pushed the rebased commit chain to the original branch so we can use this PR. If you want a clean version, re-open and merge #303.

I'm sorry, but we've spent FAR longer fucking around with git than it actually took to write the PR. I KNOW the answer is, literally, "git gud", and I'm trying 'cause I know in some sorts of development it's actually important, but at some point even my patience for procedure over actual content comes to an end. All the code is there. You want it to look a particular way, fix it yourself.

[kvark]

@icefoxen I'm sorry about your frustration with git and my update requests. It doesn't matter that you spent more time learning git than doing the PR because that knowledge is going to stay with you in the future. I'll get your commits squashed and appended to my PR as requested (by myself).

[kvark]

Closing in favor of #205

Note to @icefoxen :
With merge commits, doing my regular git pull -r upstream master would require resolving everything from scratch, which isn't the greatest option. What I ended up doing was:

git clone https://github.com/servo/euclid
cd euclid
git fetch https://github.com/icefoxen mint
git checkout FETCH_HEAD
git checkout -b mint
git reset --soft master
git commit -m "Mint integration"
git push -f origin HEAD