Sum normalized functions

[luccosta]

Resolves #71 .

This implements the functions Sum() and Normalized() in Vector4 API.

It enables:

T sumResult = vec4.Sum();
Vector4 normalVec = vec4.Normalized();

[mjcarroll]

LGTM, but there are some conflicts to resolve before it can land.

[luccosta]

@mjcarroll conflict resolved.

[mjcarroll]

Failing Bionic CI is currently expected because of ongoing infrastructure improvements.

[luccosta]

@mjcarroll is normal that ignition_math-abichecker-any_to_any-ubuntu_auto-amd64 and ignition_math-ci-pr_any-ubuntu_auto-amd64 still running?

[mjcarroll]

@mjcarroll is normal that ignition_math-abichecker-any_to_any-ubuntu_auto-amd64 and ignition_math-ci-pr_any-ubuntu_auto-amd64 still running?

Not necessarily "normal", but you can check the build queue at build.osrfoundation.org, you can see that it is a bit backed up at the moment.