WIP: Add evohome water heater

[zxdavb]

Breaking Change:

None

Description:

Adds a water_heater to the evohome integration.

Related issue (if applicable): None

Pull request with documentation for home-assistant.io (if applicable): home-assistant/home-assistant.io#<home-assistant.io PR number goes here>

Example entry for configuration.yaml (if applicable):

• uncahnged -

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly. Update and include derived files by running python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

If the code does not interact with devices:

• Tests have been added to verify that the new code works. (N?A)

[zxdavb]

@MartinHjelmare I'd be grateful if you had time for this one too.

[zxdavb]

@pvizeli OK, I rebased. This PR is not yet ready to merge to the climate-1.0 branch, but the original changes were almost exclusively limited to water_heater.py, with only refactoring of climate.py because @MartinHjelmare asked me to rename some attributes, etc.

You can see water_heater.py was just over 100 new lines, and this PR is now >800 lines changed with the migrating.

Can I just not get the water_heater merged (with some changes to __init__.py to support the next PR), then I'll do another PR for climate?

[zxdavb]

Stuck in rebase hell - will close.