There were over 150 places in *::Notify() functions that did some
dynamic_cast<SfxSimpleHint*> of which ~98% were unnecessary because the
base class SfxHint passed was an SfxSimpleHint anyway. dynamic_cast
operations come with quite some cost, so avoid if possible. Specifically
for ScFormulaCell::Notify() that created a bottleneck in scenarios where
cells were notified that already handled a previous notification. In
mass operations doing the dynamic_cast before it could be decided
whether having to act on it or not this made 2/3 of all time spent in
the Notify() call.

To get rid of that rename/move SfxSimpleHint to SfxHint and let classes
derive from SfxHint instead of SfxSimpleHint. This comes only with a
slight cost that an additional sal_uInt32 is transported in such hints,
initialized to 0, but this is neglectable compared to the huge gain.

For the rare cases where a Notify() actually expects both, an SfxHint
(formerly SfxSimpleHint) and a derived hint, this changed order of the
dynamic_cast involved so the simple SfxHint::GetId() is handled last.
Modules using such combinations can further optimize by treating the
simple SfxHint::GetId() first once verified that none of the other
derived hints use an ID not equal to zero respectively none of the ID
values the simple hint uses.

Change-Id: I9fcf723e3a4487ceb92336189d23a62c344cf0ce
Reviewed-on: https://gerrit.libreoffice.org/29205Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>