Log Message:
Changes 1.4.9:

New Features
------------
* allows rrdrestore to read input from stdin
* add documentation for RRDs::xport
* RPN operators MINNAN and MAXNAN
* --left-axis-format option to rrd_graph

Bugfixes
--------
* properly verify validity of user suplied format strings
* remove graph functions from python module when compiled without graphing
  support
* verify that only short integers are used in COMPUTE rpn expressions
* eliminate duplicate setlocale calls
* fixed endless loop and double frees in rrd_restore
* fixed missing variable initializations in rrd_graph
* fixed JSON output format to actually be valid JSON
* detect failing fallocate and fall back to seeking
* fixed format string in ruby bindings