Add Locate Control plugin

[fullonic]

Plugin based on Leaflet Locate Control

Related with issue #1098

[Conengmo]

Hi @fullonic, thanks for your work on this!

Question: the 'files changed' tab shows a lot of unrelated changes. Can you try to rebase or merge master into your branch so we can see a clean diff?

[fullonic]

hey @Conengmo, thanks for your feedback. I just did a rebase as you suggest. I tried to reduce the history of the branch and I end up creating a dirty commit. Now looks better.

I can't understand well why isn't passing all tests in Travis, but I think is not because this PR.

[Conengmo]

Thanks for updating the branch, looks good now. I'll have a look later this weekend.

[fullonic]

Thanks @Conengmo.
Doing some tests I detected a small issue with the Draw plugin. There is a extra ' " ' on line 79

folium/folium/plugins/draw.py

Line 79 in 913cf29

'download', {{ this.filename|tojson }}"

The issue isn't on the last release but on the master branch version.
I fixed in my local repo, shall I push the new commit to this PR?

[Conengmo]

Good find! Yes if you can open a pr for that, great!

[Conengmo]

Hi @fullonic, I reviewed your PR yesterday and overal it looks fine. I left mainly comments about style, to get it consistent with the rest of the code base.

Two further questions:

Can you update your branch from master? We got a fix in it that makes the tests work on Travis again.

Could you add a cell to the plugins example notebook? That notebook is a gallery of all the plugins folium has, so would be nice to show this one as well! A very simple example is enough, with one or two lines to explain what it does.

[fullonic]

Hey @Conengmo, I just added right now an example to the notebook. Let me know if it's okay or should I add more information. Thank's for your help.

[Conengmo]

@fullonic looks good! There is a tiny typo in the notebook though: 'displyed'.

Question: why or how does this plugin interfere with Draw? Can we do something about that?

[fullonic]

@fullonic looks good! There is a tiny typo in the notebook though: 'displyed'.

Question: why or how does this plugin interfere with Draw? Can we do something about that?

@Conengmo, the typo is corrected. Thanks

I have no idea why that happen. Even if I change the position of the locate button to "bottomright", for instance, it simple doesn't shows up. Only when changing the order... I didn't dig to much into the conflict because it was easy to "solve".

[Conengmo]

Thanks @fullonic! It's a nice plugin and the code is nicely done. If somebody wants to figure out why it conflicts with Draw that's welcome, but for now your warning is good enough.

[fullonic]

Thanks @Conengmo for your support and help. Was nice to make a contribution to folium!