[Users] contributing thorns to the ET

[Miguel Zilhão]

dear all,

as we had mentioned to some of you, and as discussed during the last ET telecon, Helvi and i have 
some Cactus thorns that we'd like to make available to the general ET community. these include: an 
updated evolution code that we used to evolve Proca fields (https://arxiv.org/abs/1505.00797), the 
corresponding analysis and initial data thorns, as well as a general metric evolution thorn (based 
on Uli Sperhake's Lean). we have been cleaning up the codes, and they are now available in following 
(public) bitbucket repositories:

https://bitbucket.org/canuda/lean_public
https://bitbucket.org/canuda/proca

included are some testsuites as well as some basic README files. we are currently working on a paper 
that would also serve as documentation.

it would be great if these could be considered for inclusion in the 2018-08 release. as instructed, 
we have created the corresponding ticket: https://trac.einsteintoolkit.org/ticket/2101

many thanks,
Miguel & Helvi