better axis and margin

[matyasbukva]

better axis and margin and p value handling logic.

[vandenman]

The changes look fine, but is there an issue associated with this and any figure of the pre-post behavior?

[vandenman]

please use English for comments/ variable names.

[matyasbukva]

I can't deal with this this week because I'm on a short vacation . But feel free to delete this comment anyway.

[matyasbukva]

This PR only changes the visual appearance of the raincloud plot; the underlying data and statistical results are unchanged.

How to reproduce the issue on master:

1. Add a categorical variable on the x-axis and a continuous variable on the y-axis.
2. Enable jittered points.
3. Add one or more p-values above the plot.

Observed behavior on master:

• Even when the title is empty, vertical space is still reserved for it, resulting in asymmetric margins.
• The y-axis margins are fixed to the data limits, so jittered points can partially fall outside the visible plotting area.
• When multiple p-values are added, the available top padding is often insufficient and p-value labels can overlap.

Improvements introduced in this PR:

• Empty title space is no longer reserved, resulting in symmetric plot margins.
• Y-axis margins are adjusted to ensure jittered points remain fully visible.
• Top padding is increased dynamically when multiple p-values are added, preventing overlap.

Overall, this results in a cleaner and more readable plot, while remaining fully compatible with figures created in previous versions.

[matyasbukva]

I just noticed that this wasn't merged after all...