Typed fixed vector

[wvpm]

1. Support strongly typed indices in FixedVector
2. Use index as key instead of pointers
3. Use FixedVector instead of IndexFlatMap when the key isn't required (only index and value)
4. Improve FixedVector constructors to be explicit and support moving the vector itself (not the values).

[Spartan322]

Suggested change

	struct create_empty_t { };
	struct generate_values_t { };
	struct create_empty_t { };
	static consexpr create_empty_t create_empty {};
	struct generate_values_t { };
	static constexpr generate_values_t generate_values {};

Than you can do create_empty and generate_values instead of create_empty_t {} and generate_values_t {}.

[Spartan322]

In C++ its usually preferred for the tag to come first so

Suggested change

	constexpr explicit FixedVector(const size_type capacity, generate_values_t)
	constexpr explicit FixedVector(generate_values_t, const size_type capacity)

[Spartan322]

In C++ its usually preferred for the tag to come first so

Suggested change

	constexpr explicit FixedVector(const size_type capacity, create_empty_t)
	constexpr explicit FixedVector(create_empty_t, const size_type capacity)