Split Specification into Scalar+Entropy and Vector components.

[ben-marshall]

This was decided at the meeting on September 10th 2020. The spec will be split into two pieces:

• Scalar + Entropy Source
• Vector

This is to acknowledge that the scalar and entropy source components are very nearly finished and are dependant only on Bitmanip, which is also very nearly finished. Vectors on the other hand are blocked by the base vector extension, which has a lot of work to do.

Tasks:

• Create dedicated "scalar spec" PDF document.
• Create dedicated "vector spec" PDF document.

All engineering artifacts will be left as they are, since both components can co-exist very easily. This is only a measure to get things "over the line" faster.