Render block by default on minimap

[octref]

@alexandrudima

See #4865 (comment)

[mention-bot]

@octref, thanks for your PR! By analyzing the history of the files in this pull request, we identified @alexandrudima and @egamma to be potential reviewers.

[alexdima]

@octref I think this is a matter of taste, where there is no clear right or wrong, or there is no superior or inferior option.

IMHO rendering characters is a good default, it is what both Sublime and Visual Studio do out of the box. Atom renders blocks out of the box, as they cannot render characters.

We have the option to turn rendering into blocks and I think people will choose what they like most. I personally switch the toggle on/off as I am going from high-DPI display to low-DPI display.