Frost Shield Buff, Party Size Warning, Spellblade + Whirlwind Optimization

Frost Shield: Physical Resistance removed. Now reduces all damage taken by 20%. Duration reduced from 5 to 4 seconds. This is a buff.

Added a main menu warning if your party size is greater than 2 that trying to join a map together will not work
Optimized the particularly network-deadly combo of Spellblade + Whirlwind.
Fixed Whirlwind not using the average attack speed of equipped weapons while dual wielding.