Allow PointAnnotation sampling in RandomPointSampler

[rolandnemeth000]

This is needed when sampling from a mix of points and polygons, since PointAnnotations does not have triangles.

[coveralls]

Pull Request Test Coverage Report for Build 10163683886

Details

• 2 of 3 (66.67%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.006%) to 72.673%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
wholeslidedata/samplers/pointsampler.py	2	3	66.67%

Totals
Change from base Build 9902652959:	-0.006%
Covered Lines:	2210
Relevant Lines:	3041

---

💛 - Coveralls

[martvanrijthoven]

Thanks!