Investigate the state of CMake support in dune-alugrid

Before we can switch to dune-alugrid, we have to make sure that it really supports CMake.

mentioned in issue #2 (closed)

mentioned in issue #1 (closed)

I have forked dune-alugrid here on gitlab and did

• fix the zlib issue
• add a convenience macro to add all flags from the dependent packages
• register all flags for the EnableAllPackages feature

The latter is not yet pushed as dune-pdelab-howto takes too long to build to properly test this today :D

Reassigned to @dominic

mentioned in merge request !5 (merged)

Status changed to closed by commit 97cc4626