Don't break Markdown from external sources

[frenck]

Proposed change

New lines in Markdown don't have meaning. In some cases, however, this is cool (e.g., comments on GitHub, or things like a Markdown Lovelace card).

In general, it is bad and not according to specification. Especially when loading Markdown from external sources.

This PR exposed the break option from marked in our ha-markdown component, allowing to disable this (not default) behavior in those cases.

Example Markdown:

Hello, this is a very long line,
please note the enter set in the previous line
should not be shown when rendered.

As a matter of fact, this example only contains
2 lines.

Before:

After:

Other resources still work as normal:

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

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

• Documentation added/updated for www.home-assistant.io