Task component

[royfalk]

This PR is part of a refactoring of the unit class. Specifically, it introduces the concept of resource.
A resource is any part of the game that can be used up and filled up.
The purpose of this class is to simplify code throughout the game by placing it here.
Instead of adding to health and then checking it isn't above max health, it's done automatically.
Money, energy, shield, armor are all examples of resource.

Note to reviewer:
This is a partial implementation of resource as a template. If I missed an overloaded operator or broke the rule of 0 or n, focus on that.

Code Changes:

• Have the PR Validation Tests been run?

Issues:

• Can't really die. Tried twice and ejected automatically. Couldn't respawn manually using the ; key.
• Milspec packages are broken. If you buy a ship with one, it will come with extra capabilities. You can't downgrade by adding crappy armor for example. However, if you upgrade to better armor and then sell, it will revert to 0.

Purpose:

• What is this pull request trying to do? See above
• What release is this for? Next one
• Is there a project or milestone we should apply this to? No

[BenjamenMeyer]

LGTM - one minor comment, but not blocking.

[stephengtuggy]

I've encountered the situation before where I eject instead of dying. However, we need to make sure that this doesn't happen 100% of the time, with these latest code changes.

[stephengtuggy]

Also, unfortunately, some of the CI builds broke. :-/

[BenjamenMeyer]

looks like Mac builds are breaking

[royfalk]

looks like Mac builds are breaking

Fixed now. Note that I had a non-recurring seg-fault on one unit test. Since the test was also run successfully on other builds including other mac builds, I figured this was a fluke of some kind and re-ran the build and it passed.
However, it is something to keep in mind in general and when approving this PR.

[royfalk]

I've encountered the situation before where I eject instead of dying. However, we need to make sure that this doesn't happen 100% of the time, with these latest code changes.

Opened #600 for it.