config: add absolute size / position getters / setters and window rules

[Ktrompfl]

Implements #1052.

[mahkoh]

I'd prefer for this to be a single action set-position that takes the following arguments:

• x1
• y1
• x2
• y2
• width
• height

All fields take numbers as arguments but also the string "keep", to indicate that this value should be preserved. Naturally not all combinations are valid. For example, it would not make sense to set x1=0, x2=100, width=keep, since you cannot follow all three instructions in general.

[Ktrompfl]

Is this what you have in mind or should I keep the size / position setters as separate functions in jay-config and only expose them as a combined action in toml-config?

[mahkoh]

I've only looked at the SetPosition data structure for now, not at the business logic, but I don't think it can be correct as is. The three states number/"keep"/omitted must be distinguished. Currently it seems that you conflate "keep" and omitted.

If a user sets x1=2, then I'd expect x2 to stay as is, so the window width might increase or decrease.

However, if a user sets x1=2,width="keep", then x2 should be adjusted dynamically to preserve the width.