FileFilter maps fromcol->intocol; Clean up file handling

file_filter.c:
- FileFilter no longer contains a file handle. Only stores colour mapping.
- Store fromcol and intocol arrays, instead of single array

file_util.c:
- atomic create/open with futil_create_file()
- clean up file handling

graph_reader.c:
- fix bug in loading multiple graph files, should OR node_in_cols, not cpy!

graph_file_reader.c:
gpath_reader.c:
- opening a file calls die() on error - no fatal argument anymore

test/run.sh:
- run all test Makefiles
- fixed multiple bugs in Makefiles and command line issues

libs/string_buffer.h has been updated to use MACROs for simple functions
- required updating fields {buff,len}->{b,end}

Several small bug fixes including command line arg parsing + fixing memory leaks
Add more command line tests + integrate with Travis CI