bnc#821916: Better algorithm to find placeholder shape.

Placeholder type seems to be more relevant than index.

(cherry picked from commit cc6ae367280d205a88c6f907b20b84613221ca52)

Conflicts:
	oox/source/ppt/pptshape.cxx

Change-Id: I9d6c6cad8e0a51b2385801f65d7d1c697ad7998e
bnc#880448: Improved handling of placeholder shapes

If subTitle placeholder is not found, try body instead of title.
And use body text styles instead of title, for subTitle.

Also improve PPTShape::findPlaceholder to find placeholder
with just nSecondSubType type without the same index.

(cherry picked from commit 2a7119021edea8346e4673d57cac3f051a5d0968)

Conflicts:
	oox/source/ppt/pptshape.cxx

Change-Id: I470e7268088eb989fb934007dfcf704f67d8cb1d
Reviewed-on: https://gerrit.libreoffice.org/11065
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>
(cherry picked from commit 092a3a093b11485cb3c951cb36b56ce08218f1e4)