Enhancements in Slow Defense tab:

- use of speed reducers (e.g. send 152 riders with 1 lancer)
- limitation of number of sendings to N per minute (default 3)
- replaces "max time before attacks" by "send in". default 00:00 = send immediately
- configurable error marging (for landing time), 0, 1 or 2 minutes
- Added unit type "UD+UO, except lancers".
- Added packing options, especially 200+152 every 15 mins (safe mode)
- Added an option to omit certain castles (list of commas separated strings)
- Added an option to use only certain castles (same)