Prevent occasional crash

I came across the crash by accident when checking how it works to have
multiple windows showing the same document. Pasting in lots of text
and then quickly telling LO to exit with Cmd-Q caused a crash here as
GetPostItMgr() returned NULL.

Change-Id: Ib9e636df0832a679a1d81fa3856ea0a7105a69c3
(cherry picked from commit 0eb1ef39084a978e8c2bec977ebabf6708f0c073)
Reviewed-on: https://gerrit.libreoffice.org/13219
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>
mirror fixes for fdo#78906 and deb#766788 into icu

(cherry picked from commit a66451887425ddd9387e2b25d5125916f4a35f83)
(cherry picked from commit bff0fe902686d8c126a73e1d2c914f5d65c6ffaf)

Conflicts:
	external/icu/UnpackedTarball_icu.mk

Change-Id: I9325bb28eb267b023f628e24fea216ad580759e9
Reviewed-on: https://gerrit.libreoffice.org/13220
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>
editeng: fix build

Change-Id: I64d50f1b1554f7bbb1aadffd16089be2847b765a
(cherry picked from commit d6edd18c7bda9ca6325b1abd59de0014be33a0bb)
fdo#86762 re-establish listeners to move cell broadcasters

... for UpdateReferenceOnSort=false

(cherry picked from commit 6c2111f17089eb667bf526561d7667d17825e822)

Conflicts:
	sc/source/core/data/table3.cxx

fdo#86762 broadcast also empty cells after sort

(cherry picked from commit 08793e08c7e9cefe594c49130f782725e386c463)

Conflicts:
	sc/inc/column.hxx
	sc/source/core/data/column.cxx
	sc/source/core/data/document.cxx
	sc/source/core/data/table2.cxx
	sc/source/ui/docshell/dbdocfun.cxx

fdo#86762 re-establish listeners on moved broadcasters

...  also in SortReorderByColumn() similar to SortReorderByRow()

(cherry picked from commit e119f3883513aeaa49f332362620e955dc8b453f)

Conflicts:
	sc/source/core/data/table3.cxx

e275a754c530d6039ed14304900dd71416f36e46
7665dcc90d70fcf3b08bef0adb9ab6aaff1cdcdf

Change-Id: Id90288660e317d6e47ee01ee3b5ff9058cfa18df
Reviewed-on: https://gerrit.libreoffice.org/13275
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
Bump version to 4.2-20

Change-Id: I9838eede17e52ba377f072f967acf65f081d1985