Changes

Amiga: (68k) OM_SET on LAYOUT_AddChild must use SetGadgetAttrs I've
changed LAYOUT_RemoveChild too to ensure the layout is protected OM_SET
on LAYOUT_AddChild wasn't supported before v47 so this likely worked by
luck on <OS3.2 Will require v47 on chris/ndk32 branch as dropping
OS3.5/9 support there

Amiga: Use window.class built-in snapshot for cookies window

Amiga: Snapshot history window using window.class built-in function

Amiga: Add window snaphot to local history window via window.class
built-in

Amiga: Move hotlist window snapshot to window.class native

Amiga: Enforce some minimum space gadget sizes to avoid windows being
too small

Amiga: Fix favicon mask on OS3

Amiga: more sensibke default windw sizes

Amiga: Setting WA_Width/Height is equivalent to InnerWidth/Height
Removed TODO and adjusted tag names for clarification

Amiga: add helphint to hotlist star button

Amiga: Rewrite bitmap_render so it works on OS4 and OS3 (currently only
with RTG)

Amiga: Don't invert alpha if there is none

Amiga: Enable drag'n'drop on OS3

Revert "Amiga: Enable drag'n'drop on OS3"
This reverts commit 3cd3d9c8d41d32824dee1837a321dbb36d79745b.

Amiga: When clearing the clip region, actually set it to clip to the
size of the underlying BitMap

Amiga: Create Region before attempting to use it

Amiga: Disable bitmap_render on OS3 as it is unstable

Amiga: Increase default window sizes