TextLineSegment gets shape() call before layout() if mscore used as converter

Works fine if using gui, but calling

mscore segf2.mscz -o x.ogg

Fails with a segfault on layout.cpp 3422 -> textline.cpp 137
Some debugging reveals npoints is a very big number, meaning it has been left uninitialized, meaning it has not been layout() before 3422 gets called.