Better icon scale

Better icon scale

The icons should be scaled if their size is "max_size - ~3 pixels".
Tipically, max_size is 64 pixels. With the current wIconValidateIconSize
the max size for an icon is "64 pixels", then the icon don't have border
and is ugly. This problem is in the dock icons and in the switchpanel.

The new wIconValidateIconSize function don't use the fixel value of 64
pixels, uses the argument max_size to get the final icon size. The icon
is scaled holding the aspect ratio and reserve ~2 or ~3 pixels to hold
left space to the icon border. Now the icon is inside the icon space,
with border.

This patch removes the preprocessor option of DONT_SCALE_ICONS, because
all the icons should be scaled if needed, to hold a beatiful interface.