refactor init handling to be easier to grasp

the if(env) dance was fine when we only had KDE_DEBUG, today this is causing more headache than it needs to

the mountain of drkonqi conditions is now hidden behind a shouldUseDrKonqi() helper checking whether drkonqi should be auto-initialized. the conditions which control crash handling at large have been isolated into shouldHandleCrash() with an eye towards shouldWriteMetadataToDisk which should probably also be conditional on it