Various odds and ends to prepare for "stable spec" vote

[Jose Moreira (joseemoreira)]

These changes address the following issues:

1. Clarified the use of lambda=0, both as a write value and a read value.
2. Clarified computational semantics of microscaled forms with integer inputs.
3. Revised the note on effects of double rounding when computing and accumulating dot-products.
4. Adjusted declaraion of the _as_e{S} forms for tile loads/stores so that base pointer has a compatible type.
5. Added forward references to guide the reader through the document.
6. Cleaned up some normative notes.