2b1c567 To prevent high cpu usage we should update list only once in MASTERNODELIST_UPDATE_SECONDS seconds or MASTERNODELIST_FILTER_COOLDOWN_SECONDS seconds after filter was last changed. Also changing date/time format - QDateTime ToString() is way to slow for a list of thousands items, using DateTimeStrFormat instead. UI should work much smoother on mainnet now.
- set initial columns size
- use resizable columns
- use theme-dependent masternodes icon (placeholder, should be replaced)
- removed unused event binding
- capitalization, more verbose ui element names
