This improves performance and memory footprint,
particularly when using NEdit to view very large files.
It replaces calls to BufGetAll() with BufAsString().
Where the full buffer text is required in a read-only
context, instead of making a string copy of it, just
use its content directly (having made sure the extra
gap space does not appear inside this content).
See also patch
1191453 Avoiding buffer copying in macro search
which introduced BufAsString(). It was added to the
NEdit source on 2006-Apr-21.
This patch was created following comments about
suspected malloc errors by Jeno Balasko (discuss list,
(I've been using this patch for some time and it
appears pretty solid.)