Fixe fence gates with fence corners (allow checking for further flags).
[API CHANGE] Add debug flags to check data [missing: use that one].

For debug output now data.debug is used instead of config.debug, so the
data is initialized with the config.debug value. As an effect of this,
removing the data or reloading will override flags that have been set by
means of API-access only.

Affected:
* Adds getDebug and setDebug to ICheckData.
* Adds appropriate configs to all constructors of check data.
* Some per-check debug flags have been removed.

Extras: 
* spaces
* import cleanup.