Changes to Attribute to support .source(). Start of tests.

[#68910816]
#959
Finished writing test for Attribute::source(), etc. Test passes.
Start at registering Attribute sources.
Merge branch 'develop' into 68910816-959-RefactorDataPointOutputAttributes
[#70939478] Fix units #1017
Changes through analysis library. Should be ready after I fix the osp (project).

[#68910816]
Merge branch 'develop' into 68910816-959-RefactorDataPointOutputAttributes
Initial cut at osp updates.
New osp for backwards-compatibility testing.
Final changes to get this working right.
Ruby test fixes.
Removing essentially empty files. (These showed up as Ruby test failures for me.)
Merge remote-tracking branch 'remotes/origin/develop' into 68910816-959-RefactorDataPointOutputAttributes
Merge remote-tracking branch 'remotes/origin/develop' into 68910816-959-RefactorDataPointOutputAttributes
Updating to new version numbers
Initial attempt at SetpointManager base class

Has odd compile error currently
Fixing build error
SetpointManager base class updates
Fix build errors, apply new base class, add tests

Fixed various build errors.

Applied the base class to SetpointManagerScheduled,
SetpointManagerOutdoorAirReset, and
SetpointManagerFollowOutdoorAirTemperature
Add unit tests, add MixedAir and SingleZoneReheat

Fix various bugs, add unit tests, add SetpointManagerMixedAir, add
SetpointManagerSingleZoneReheat