Standardised editor setting for screenshots

[coolya]

Right now screenshots are taken with the editor settings of the user. Which means font, font size, etc can vary depending on which user is uploading the gist.
Ideally we want to use the same settings on the client side to generate the screenshot to ensure a consistent look at the website. Extremely large or small font sizes can make it hard to read the screenshots at the website. Especially large fonts can easily render the preview feature on the front page useless because we might only see one or two lines of the gist.

The images are produced in ide-plugin/src/main/kotlin/cloud/skadi/gist/mps/plugin/EditorAsImage.kt