more usum prep
don't allocate empty array on every savefile creation (use linq All
comparison)
add percent seen/caught savefile properties for data analysis purposes
999 is true max, set suggested give count to -4 from max (or 1).
Apply giveAll's max value restriction to modifyAll
Prevent giveall/modifyall for PCItems/FreeSpace due to mixed item types.
Closes#1228Closes#1227