Add bindings for circle-sort-key

[chloekraw]

<changelog>Added methods to set and get the sort key of features in a CircleLayer at runtime. Features with a higher sort key will appear above features with a lower sort key.</changelog>

Fixes #197

[chloekraw]

@LukasPaczos @tobrun I noticed running the script included changes that are also in #319. Should I manually override the changes that don't relate to circle sort key in a new commit? Let me know what the best way forward is.

[LukasPaczos]

Great work @chloekraw @Chaoba!

Because of the generation script changes needed to expose include LocationIndicatorLayer, we cannot fully use the script right now and include all the available bindings. The current contents of the PR look good to me, so let's go ahead and merge and I'll resolve the conflicts when rebasing #319.

[chloekraw]

@LukasPaczos thanks! Looks like @Chaoba’s commit removed the non-circle-sort-key changes so hopefully you don’t run into too many merge conflicts when you rebase.