[FEATURE REQUEST] Convex and concave polygons

[LdDl]

Is your feature request related to a problem? Please describe.
Along with virtual line virtual polygon are needed.
They can give us:

1. Traffic "lane" control
2. Monitoring area of interests
3. Estimating how much time object were in certain area (well, it could be analyzed in postprocess via track information also)

Describe the solution you'd like
Implement VirtualPolygon:

• Constructor
• Determine if polygon either convex or concave
• Check if point in polygon (well, for convex and concave polygons algorithms may differ)
• Check if blob has entered polygon
• Check if blob has left polygon
• Scale function

Describe alternatives you've considered
nope

Additional context
We need also:

• Option to configure polygons
• Match polygons' Euclidean coordinates to WGS84
• Write test for math calculations (determine if point is inside of polygon is not easy task for some types of polygon)

[LdDl]

Convex is done I believe.
Now we are doing some other things before we are back to concave polygons.