accessibility: don't crash if the TableControl is dead

AccessibleGridControlAccess: clear the m_pTable member in dispose() so
it is no longer accessed later.

Change-Id: I490c84ce1bee55c9c69eb29b81ddfbe808301797
(cherry picked from commit 449e0c9c7378ba32039bd5934c26011d682a8a91)
ChildrenManagerImpl::AddShape: do not use member after releasing mutex

This crashed here once during some JunitTest with an rDescriptor that
did not match maVisibleChildren.back().
[The mrContext member used here is const so shouldn't cause problems.]

Change-Id: I31e54b166badef6472127c64f0a4f49c51c73b30
(cherry picked from commit ebb6c4407da2f8e913f1520b61a36ca3a4b54a7e)
sax: avoid usage of double for parsing nanoseconds here too

Change-Id: Iddf93a116cb333db6465a915dae692c33a60241a
(cherry picked from commit 64575a5b91b0fae6283b9ad8b1356e76caa34b45)
fdo#72452: ODF import/export: fix handling of style:page-number

Class XMLNumberWithAutoInsteadZeroPropHdl (which appears to be used only
for this attribute) needs to be adapted to the change that
"PageNumberOffset" value 0 is no longer invalid; use "void" value for
invalid instead, which appears more appropriate anyway.

Unfortunately the type of style:page-number is positiveInteger so
writing 0 would be invalid; write "auto" instead for now.

Change-Id: I9621ea201fd928087b863c562607c3d77a3b0269
(cherry picked from commit 22355042a6fc7aecf3caab69b3fa3be1430b697f)