Fix histogram removing last spurious bin

[VictorVelarde]

This is a use case to detect the issue:

       const features = [
            { field: 1 },
            { field: 2 }, { field: 2 },
            { field: 3 }, { field: 3 }, { field: 3 },
            { field: 4 }, { field: 4 },
            { field: 5 }            
        ];

        const ticks = [2, 4, 6];

        const h = histogram(features, 'field', ticks, AggregationTypes.COUNT);        
        console.log(h); // [1, 5, 3, 0, 0]

Results

Histogram results should be interpreted as:
>=MIN to <2 --> 1 item
>=2 to <4 --> 5 items
>=4 to <6 --> 3 items
>=6 to MAX --> 0 items

BUT there is an extra bin, with value 0, that shouldn't be there (unless I'm missing something non obvious)

[VictorVelarde]

We still have to fix tests on viewportFeatures. that I missed

[coveralls]

Pull Request Test Coverage Report for Build 667549435

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.04%) to 79.292%

---

Totals
Change from base Build 661969161:	0.04%
Covered Lines:	583
Relevant Lines:	698

---

💛 - Coveralls