Implement "event" evaluation strategy for "point" granularity

[sarusso]

Granularity: datapoint

GT)    =========
MO)     =======
tp: 1/1
fp: 0

GT)    =========
MO)          =======
tp: 1/1
fp: 1

GT)    =========
MO)  =======
tp: 1/1
fp: 1

GT)    
MO)  =======
tp: None
fp: 1

GT)    
MO)  ====  ===
tp: None
fp: 2