fix CPPFLAGS handling in configure.ac, closes #674
fix a spelling error in drl_layout.cpp
remove unused test target from root Makefile.am
configure.ac: fixed an AC_LANG_PUSH instance that was not paired properly with an AC_LANG_POP
fix failing test case when ARPACK is external, closes #676
Python: moved a variable declaration to the beginning of its function, closes #679
removed confusing warning thrown by the GraphML reader when there is an ID vertex attribute in the file
finished handling of Boolean attributes in the C attribute handler
default attribute values are now handled in GraphML files
GraphML parser now handles XML namespaces properly; closes #685
R: use useDynLib instead of library.dynam, for devtools
R: try to use roxygen2
R: convert most docs to roxygen2
R: remove .o files in subdirectories before building package

These are not ignored by R CMD build, apparently.
R: various docs/roxygen fixes
R: graph.ring -> g_ring
Renaming most constructors, #686