Explicit gboolean parameters sanitization
Document that we want to sanitize the boolean parameter, provide an explicit way to do so via the HDY_ENSURE_BOOLEAN() macro function, and apply that sanitization where relevant.
Please note that I am not completely sure about the design of this, e.g. I am not sure
HDY_AS_BOOLEAN is relevant, and maybe we want to have the macro in lower case to better fit in the preconditions.