Make regular grid color configurable

[ChristianFeldmann]

Is your feature request related to a problem? Please describe.
In some situations, the color of the drawn grid is not visible (e.g. dark sequence).

Describe the solution you'd like
It would be nice to be able to select the color of the grid.

Describe alternatives you've considered
No

[adamws]

Hi, I think this feature already exist: File->Settings->General->View Grid Line Color

Or perhaps it's something different you are looking for.

[ChristianFeldmann]

:D Awesome I forgot that I already added this. But I think the positioning of the setting could be a bit better. It would be cool to also be able to select this through the context menu.

[adamws]

Here is my proposition 6e72a09

grid-color.webm

Still need to figure out how to synchronize with Settings dialog window.

[ChristianFeldmann]

Its actually a tiny bit easier then your code. Please see the PR. Once it compiles I will merge it.

[ChristianFeldmann]

Alright I merged this.