GC3Pie 2.6.4 released

[Riccardo Murri]

Dear GC3Pie users,

We are proud to announce release 2.6.4 of GC3Pie. This is
a bugfix release: the code in 2.6.0 introduced some changes
to core objects which made it impossible to read sessions and
tasks created by pre-2.6 GC3Pie with the GC3Pie 2.6.0--2.6.3.
This backwards incompatibility has now been fixed, and GC3Pie
2.6.4 can load tasks saved with GC3Pie 2.4.x and 2.5.x.

Note that the fix is only available on Python2, because Python3
has a completely different implementation of the `pickle` library.
However, since Python3 was not supported in pre-2.6 GC3Pie,
this should not be an issue in practice.

As usual, additional information is also available through
the GC3Pie documentation website: http://gc3pie.readthedocs.io/

Yours,
the GC3Pie development team