add complex scalar and vector types throughout docs #433
Description
The section titled Type Inference does not mention complex types, unlike the Data Types chapter proceeding it. This information may be better divided up among that chapter and the Extra Grammatical Constraints chapter.
- add complex types to Type Inference section
- add complex vectors, row vectors, and matrices everywhere, and discuss promotion
- add I/O description (was doc JSON (and R dump?) format for complex numbers #386)