CMake use of UG_PARALLEL is wrong

Hi all,

within the cmake/modules/DunePdelabMacros.cmake, the PDELAB_SEQUENTIAL_UG is set to 1 even though the parallel UGGrid is built. Instead of

if(NOT (UG_PARALLEL STREQUAL "yes"))

use

if(NOT UG_PARALLEL)

because the variable is set to UG_ENABLE_PARALLEL in dune-uggrid which can be used in boolean expressions directly.

Best, Christian