[Lazarus] Ann: TButtonEdit as replacement for TEditButton

[Bart]

Hi all,

As per r44623 (trunk) the new TButtonEdit component replaces the
TEditButton component.
The new TButtonEdit is designed as "Grouped Control", so it should
properly anchor and align.
(You need to clean build Lazarus in order to update the componentpallette.)

TEditButton is, for the time being, an alias for TButtonEdit, so that
forms with a TEditButton still can load.
If you find any regressions please report them in the bugtracker.
For the time being you can build Lazarus with -dUSEOLDEDITBUTTON to
still use the old implementation.

I would like to thank Derit Agustin for the initial implementation of
the new TCustomButtonEdit.

Bart