* Add error checking for DS name length
* Update RrdDefinition.php
* Move greater than 19 length test to unit test
* Remove unused variables
* Remove duplicate unit test, and update test for empty name
* Typo
* Remove extra assignment
* ...
* Remove unused items
* Update RrdDefinitionTest.php
* Update RrdDefinition.php
* Delete InvalidRrdNameException.php
* feature: Allow customisation of rrd step/heartbeat when creating new rrd files
* revert defaults
* added docs + webui config option
* Move RrdDefinition to an Object to make them easier to create and remove the possibility of typos.
* Fix style/lint issues and missing use statements
* 3 more missing use statements
* updated doc + moved schema file