Refactor: Public APIs should be documented

[AlexeyGirin]

Problem:
Public APIs should be documented

Why is this an issue?
Public APIs have to be documented in order to be used by customers.
APIs documentation is typically generated using a tool, such as Sphinx.

Exceptions that do not require documentation:

• Member functions marked with identifier override. Assumption is that they are documented in the base class.
• Member functions marked with specifier delete or default.
• Member functions defined outside of a class/struct. Assumption is that they are already documented inside of the class.

Following items are considered as public API:

• classes/structures/unions
• class/structure/union members (public and protected only)
• template declarations
• enumeration declarations
• enumeration definitions
• typedef/alias declarations
• functions (global scope)
• variables (global scope)

The following code illustrates a well documented class (example provided for python language):

    def setOption(self, option, value1, value2=None, value3=None):
        """Sets option value

        Args:
            option (str): option name
            value1 (int, str, bool, float): option value
            value2 (int, float): option value for tuples. Optional, defaults
                                 to None.
            value3 (float): option value for triple. Optional,
                            defaults to None.

        Raises:
            IndigoException: if option does not exist
        """

        opt = option.encode()
        if (
            isinstance(value1, float)
            and isinstance(value2, float)
            and isinstance(value3, float)
        ):
            IndigoLib.checkResult(
                self._lib().indigoSetOptionColor(opt, value1, value2, value3)
            )
        elif (
            isinstance(value1, int)
            and isinstance(value2, int)
            and value3 is None
        ):
            IndigoLib.checkResult(
                self._lib().indigoSetOptionXY(opt, value1, value2)
            )
        elif value2 is None and value3 is None:
            if isinstance(value1, str):
                setOpt = self._lib().indigoSetOption
                value = value1.encode()
            elif isinstance(value1, int):
                setOpt = self._lib().indigoSetOptionInt
                value = value1
            elif isinstance(value1, float):
                setOpt = self._lib().indigoSetOptionFloat
                value = value1
            elif isinstance(value1, bool):
                value1 = 0
                if value1:
                    value1 = 1
                setOpt = self._lib().indigoSetOptionBool
            else:
                raise IndigoException("bad option")
            IndigoLib.checkResult(setOpt(opt, value))
        else:
            raise IndigoException("bad option")

Problem locations:
api/c/bingo-nosql/bingo-nosql.h