fixed copy constructor of line element where neighbours were not copied
Merge branch 'master' of https://github.com/ufz/ogs
add dimension, n_all_nodes, n_base_nodes to element classes as static const
use the static const variables in getoDimension() and getNNodes()
Merge pull request #384 from norihiro-w/add-static-const-vars-to-elements

Add static const variables to elements