Free speedups

[redmoogle]

The changes in DreamValues.cs provide about 20-30% speedup on equals comparison (900-1000 ticks vs 1300)
The changes in DreamList.cs maybe provide 1-5% speedup (get_count was using about 1.83% cpu)

tested using

var/list/L1 = list()
for (var/i in 1 to 100000)
    L1 += new /datum

var/start = world.timeofday
var/list/L2 = list()
for (var/i in 1 to 100000)
    var/key = L1[i]
    L2[key] = 1
world.log << world.timeofday - start