[Lazarus] High-DPI TImageList

[Werner Pamler]

The high-DPI imagelist adds a new entry to the lfm file, "BitmapAdv". Is 
this really absolutely necessary in all cases, for example if the 
imagelist contains only standard-resolution images? The problem is that 
once a form with an image list has been opened by Laz trunk it cannot be 
opened by Laz 1.8 or older any more without an error message and the 
need to remove this new entry.  In particular, this is an issue for 
third-party components where the author must be very careful to save 
demo forms with Laz 1.8, not with trunk.

I remember I had the same argument with the addition of 
"Application.Scaled := true" to the lpr file, but here portability could 
kept by putting it into an {$if lclversion >= 1090000} directive. In the 
lfm files, however, such directives are not allowed.