Log Message:
Updated databases/rrdtool12 to 1.2.29

Features:

- a second axis can now be displayed in rrd_graph. look for
  documentation on second-axis. feature was sponsored by VoltWerk.

Bugfixes:

- rrd_fetch: is more careful when seeking. it should not try to seek
  outside the file anymore.

- rrd_graph: CDEF:x= raises an error now and does not segfault

- rrd_graph: --font TITLE:12: problem fixed (affecting cacti)

- rrd_graph: make VDEF work with SHIFT (bug #177)

- rrd_xport: make it work when exporting datasources without
             uniform step size.

- rrd_tool:  rely on function return values and not on errno.  (bug #176)