sdcollectd has been changed to make the parsing of incoming idle report
packets more robust.  This should squash all existing vulnerabilities on
the packet reception path.

Changes:

* NULL terminate the incoming packet buffer
* move from strcpy to strncpy.
* switch from strtoul, strtod, etc. to sscanf with explicit field lengths.
* Multi-level parsing of packets into records, then key/val pairs,
  then individual key and value parsing/checking.