Add diagnostics functions: proj4 ver. & Inv. Hammer

[micahcochran]

This is a refactor of the package_version function to move getting the proj4 version number into a new function, proj4_version. check_proj_inv_hammer function is added for checking if the inverse of the hammer projection is available (which should be in the yet to be released proj.4 version 4.9.3).

check_proj_inv_hammer() and proj4_version() are intended to end up in setup.py, but may provide some use in the main basemap library. Due to that reason, the imports are mostly self-contained for the function.

So, Proj.4 verion 4.9.3 has not been released, nor has the current development version of pyproj which has code that raises a RuntimeError when a projection's inverse function isn't available (pyproj 1.9.5.1 and before will segfault). At the moment, I'm a little uncertain about putting these the check_proj_inv_hammer() into setup.py without one of the two libraries being released. This effectively requires installation one of the development versions for the check_proj_inv_hammer function to pass the test, otherwise they risk a segfault. This originates from discussion in PR #240.

Editing setup.py seems a little daunting because I'm a bit overwhelmed by what all setup.py can do/should do. setup.py seems to work like a swiss army knife by doing a couple tasks well and other tasks not so well.

Here are my local test results of the functions, which where copied an pasted into ipython:

In [3]: proj4_version()
Out[3]: '4.9.2'

In [4]: package_versions()
Out[4]: BasemapPackageVersions(Python='2.7.4 (default, Apr  6 2013, 19:54:46) [M
SC v.1500 32 bit (Intel)]', basemap='1.0.8', matplotlib='1.5.1', numpy='1.10.4',
 pyproj='1.9.5.1', pyshp='1.2.3', PROJ4='4.9.2', GEOS='3.5.0-CAPI-1.9.0 r4084',
OWSLib='not installed', PIL='not installed', Pillow='not installed')

In [5]: check_proj_inv_hammer()
Out[5]: 'Unknown'

In [6]: check_proj_inv_hammer(True)
Out[6]: True

[WeatherGod]

Ok, this is an incremental improvement of the diagnostic functions. A nitpick: the double-negative for segfault_protection_off made me have to read the logic twice before I got it.

[micahcochran]

I can understand the confusion. In a few days, I'll do a commit to update the flag variable to just segfault_protection.Thanks for the quick feedback.

[micahcochran]

I changed the parameter's name to segfault_protection and made another commit.

IPython console

In [3]: check_proj_inv_hammer(segfault_protection=True) # default
Out[3]: 'Unknown'

In [4]: check_proj_inv_hammer(segfault_protection=False)
Out[4]: True

In [5]: check_proj_inv_hammer()
Out[5]: 'Unknown'

If you have an older version of Proj.4 or a version without the inverse hammer patch applied it will segfault Python.

[micahcochran]

Thanks.