The basegfx Triangulator is used in slideshow with canvas to triangulate
the mask geometres. This uses tools::isPointInTriangle which uses
basegfx::tools::arePointsOnSameSideOfLine. This uses the cross product
to solve and for tests against zero the fTools::equalZero call. The
triangulator then uses the more precise rtl::math::approxEqual to test
if one of the points of the triangle is equal to the test point.
In rare cases this can lead to a position where a point is seen as inside
the triangle wrongly because it is not detected as equal to one of the
triangle points. To solve, use increased accuracy.

Change-Id: I73e12b711f14d4c48e829d5db1cadefa0917c19b
Reviewed-on: https://gerrit.libreoffice.org/19925Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>