Strict latest option and keep unreleased option

[eMarek]

Added options:

• strictLatest - Entry of latest version must be present in order to get correct changelog. Set this option to false if you expect latest version without logs.
• keepUnreleased - It leaves "Unreleased" title row unchanged if set to true.

Changed that plugin does not force you to have so many new lines between version title and changelog entires.

Bugfix where changelog filename was not properly applied across the plugin.

[eMarek]

@webpro, can you take a look at this pull request please?

[webpro]

Thanks @eMarek!

I've added you as a maintainer to the project. Not sure if you even want this, and whether "maintainer" gives you enough permissions, but we'll see.

[eMarek]

Ok, thanks!