jeremyong/klein: v2.0

New semantic release due to breaking compatibility.

• Entity type has been removed due to compiler inability to properly constant-fold interior expressions.
• Operators have been promoted to first-order types.
• A number of operators have been specialized for various types for improved throughput/latency.
• Perf analysis has been updated.
• Motors can now be constructed from a screw axis, angle, and displacement.
• A preliminary dual number type as been added.
• The exp/log methods have been promoted to free functions and now have strongly typed return values.
• The project function has been added to simplify various projections.

Some operations that were previously permitted are no longer supported due to a fully general underlying "multivector" class (formerly known as entity<PMask>). Operation overloads are now added individually. This enables another class of optimizations because type safety ensures that certain components of SSE registers are exactly 0.

Summarizing:

• Compile times reduced due to very minimal usage of templates and constexpr branches
• Speed improvements in most situations
• Increased type safety in a number of situations