Minimum Cython version updated

[pelson]

Description

It seems that #1251 means that we now depend on Cython 0.29+.

The compile error I got with 0.28.5 (Linux, GCC 4.4.7):

cythoning lib/cartopy/trace.pyx to lib/cartopy/trace.cpp

Error compiling Cython file:
------------------------------------------------------------
...
        else:
            geom = GEOSGeom_createCollection_r(handle, GEOS_MULTILINESTRING,
                                               &geoms[0], geoms.size())
        return geom

    cdef list[Line].size_type size(self):
        ^
------------------------------------------------------------

lib/cartopy/trace.pyx:173:9: 'list[Line].size_type' is not a type identifier

We should either try to relax this version dependency, or document it (either is fine IMO).

cc @QuLogic

[QuLogic]

That's odd; both Travis and AppVeyor build against Cython 0.17.

[pelson]

Hmm, yes indeed. Perhaps it isn't as simple as the Cython version. I was using a pretty old GCC there, so there may be more to it. For others that come across this issue (via Google), upgrading to Cython v0.29 did solve the issue for me.

[QuLogic]

Here's a build where I pass --no-build-isolation and it fails as yours did: https://travis-ci.org/QuLogic/cartopy/builds/479829383 This switch seems to have been quietly hiding some subtle bugs.

[QuLogic]

I'd like to see if we can still support Cython 0.28 as that's what's in current Fedora and Debian testing.

[pelson]

I'd like to see if we can still support Cython 0.28 as that's what's in current Fedora and Debian testing.

With #1264 you don't need Cython at all if you are using the sdist? Is that helpful?