[-_-] Custom Type Examples

Description:
This script shows an example use of new Pinescript's feature called User Defined Types, which can be seen as analogue of <struct> from C++ or <dataclass> from Python. It is not an indicator for technical analysis, and serves only as an example of how to use the new feature mentioned above.

In the script I define 4 custom types and a custom initialisation function for each:
- Point (represents a coordinate with x -> bar_index, y -> price)
- Tria (creates a triangle using <line> objects and <point> objects as coordinates of 3 points)
- Path (creates a path-like object from an <array> of <point>)
- Trade (creates a visual representation of a Long/Short trade with set Take Profit and Stop Loss, and displays an info label with realized Profit/Loss)

I'd personally like to see this feature improved by adding methods (so that we could, for example, define functions inside a custom type), which could be an analogue of classes from other programming languages.