Bugs

* The next/prev functions are not coordinated with the data saved to the rrd
    files.  As a result, next/prev do not function as one might expect.

Desired features.

* Custom reports - combine graphs of various types on one page.
  - This is partially addressed by showhost.cgi (all graphs for one host on a
    page) and showservice.cgi (all graphs for one service on a page).
* Customize rrd options for split graphs.
* Red bar in graph to indicate missing data.
* Installer - that can configure Nagios (must work with Nagios 2.12 and 3.x).
* Stacked area graphs like http://oss.oetiker.ch/rrdtool/gallery/ramUsage.png.
  - This requires configuring a custom graph type for a specific data set,
    since other data sets may not work well with an area graph type.
* Custom unit labels on the graphs.
* Units specification beyond what Fixed Scale does.
* Either do it all with javascript, or do it all without. Right now there is a
  mix of stuff, specifically the 'update graphs' button does not need to be
  done with javascript.