Improve icon scaling algorithm to scale down more often

[roblillack]

This PR includes the following changes:

• Ensure, the "enforce icon margin" algorithm is also used when getting the application icon from the wm_hints to ensure that modern application that provide an icon >= the specified icon size will have this scaled down a bit smaller than the configured icon size (Firefox, Edge, VSCode, MATE Power Statistics in the Example below)
• Enforce this icon margin by default (I can still be turned off using WPrefs)
• Fix a small bug which--when scaling icons, but enforcing the margin is turned off--in calculating the necessary icon size.

The result looks like this:

Note, how application icons too large before are scaled to fix the configured app icons size better now.

There is a tiny little regression for the NEdit icon (b/w bitmap) as this icon includes the padding in the image data and is scaled without a reason. This can be improved in the future using some edge detection algoithm

[gryf]

Hi. Could you propose this patch on upstream wmaker?

[roblillack]

Hi. Could you propose this patch on upstream wmaker?

Done. Thanks!