[Lazarus] IDE Messages window uses much CPU when building a project on Win32

[cobines]

The output filter that processes compiler output often issues empty
BeginUpdate/EndUpdate sequences without actually making any updates.
It also updates very often, usually 15 times per second, so it
constantly switches in and out of update mode and that causes the
whole treeview to be repainted very often. For me personally adding
new lines once per second would be enough and progress is not needed
at all.

I think it can be changed so that Begin/EndUpdate are only called when
actually there is something to update. Plus an option could be added
to disable displaying progress line.

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cobines