update configure for automake 1.14

 - fixes a warning about missing AM_PROG_AR
 - makes warnings non fatal because 1.14 warns about the use of
   subdirectories
Merge pull request #125 from lonvia/configure

update configure for automake 1.14
pt_diagrams: ignore nodes with public_transport=platform

The assumption is that there is a public_transport=stop_position nearby.