Core: signal save database event
Core: add functions to API
Core: let update the stored history limit
Organism alarms: rename attribute
Organism alarms: let update the stored log limit
Organism alarms: add functions to API
wx Tasklist: fix race bug
wx Tasklist: save configuration only _after_ the exit is confirmed
wx GUI: refresh session without event
wx GUI: remove unused event
wx GUI: add database properties panel

Fixes #38
Addresses #37
wx GUI: Let plugins add database properties
wx Alarms log: add interface for changing the log limit

Fixes #37