Yaml regex experiment

[TomasVotruba]

Since more people asked about this, it deserves reopening

Before we though about using parsing/dumping/modifying ast of yaml #17

Maybe it would be enough to use regular instead.
https://www.google.cz/search?q=regex+replace+word+folowed+by+another+word&oq=regex+replace+word+folowed+by+another+word&aqs=chrome..69i57.15559j0j7&client=ms-android-google&sourceid=chrome-mobile&ie=UTF-8

"key:\s+old_subkey" to "key:\s+new_subkey"

[TomasVotruba]

• shopsys/shopsys@c035785#diff-b401dbbf5297ae59e7fbca6571583a14

• /~https://github.com/symfony/symfony/blob/3.0/UPGRADE-3.0.md#security

Main cases?

• try preg_replace... on first match stop
• turn to dummy rettors, nothing complex

key:
    another_key: old_value

key:
    anothe_key: new_value

into

key:
    old_key: value

key:
    new_key: value

[TomasVotruba]

Init by #509