rename alu2d to 2d

dune/alugrid/src/2d/Makefile.am.include

+alu = alu2d
+alu2dhdrs= 2d/grid.h 2d/handle.h 2d/listwalk.h 2d/triang.h 2d/vmmap.h 2d/vtx_btree.h 2d/grid_imp.cc 2d/vtxprojection.h

dune/alugrid/src/Makefile.am

 
-SUBDIRS = serial parallel duneinterface alu2d 
+SUBDIRS = serial parallel duneinterface 2d 
 
 # here the headers to install are defined 
 include serial/Makefile.am.include
 include parallel/Makefile.am.include
 include duneinterface/Makefile.am.include
-include alu2d/Makefile.am.include
+include 2d/Makefile.am.include
 
 # work arround for automake versions < 1.8 
-ALUGRID_CPPFLAGS = $(ALL_PKG_CPPFLAGS) -I$(srcdir)/serial -I$(srcdir)/parallel -I$(srcdir)/duneinterface -I$(srcdir)/alu2d
+ALUGRID_CPPFLAGS = $(ALL_PKG_CPPFLAGS) -I$(srcdir)/serial -I$(srcdir)/parallel -I$(srcdir)/duneinterface -I$(srcdir)/2d
 
 # build libALU3dGrid 
 lib_LTLIBRARIES = libalugrid.la

dune/alugrid/src/alu2d/Makefile.am.include

-alu = alu2d
-alu2dhdrs= $(alu)/grid.h  $(alu)/handle.h  $(alu)/listwalk.h  $(alu)/triang.h $(alu)/vmmap.h  $(alu)/vtx_btree.h  $(alu)/grid_imp.cc $(alu)/vtxprojection.h