Fix MeshLayerMapper compilation
This fixes compilation error introduced by removing the empty constructor in the MeshLayeredMapper
.
This happens with the mac's compiler, which is more strict and produces the following error:
<.../ogs/Applications/DataExplorer/DataView/MeshLayerEditDialog.cpp>:261:25: error: default initialization of an object of const type 'const MeshLayerMapper' requires a user-provided default constructor
MeshLayerMapper const mapper;
^
<..../ogs/Applications/DataExplorer/DataView/MeshLayerEditDialog.cpp>:308:25: error: default initialization of an object of const type 'const MeshLayerMapper' requires a user-provided default constructor
MeshLayerMapper const mapper;
^
... but the referred objects are not required at all: removing them.