Merge pull request #32 from clobrother/master

Few patchs to merge our codebase
Rename "decolore" option

Make its function clearer, and also keep previous behavior if the
config option is not defined.
Align legend with brightening
Merge pull request #33 from green525/master

Align legend with brightening
Fix config backward compatibility
Fix graph sizing, improve config

Use full-size-graph option in recent RRDTool versions to avoid scaled
graphs. Introduce config defaults file to avoid hairy isset() logic for
new options. Make graph sizes configurable.