Fix pic placeholder and placeholdername
Fix pic placeholder and placeholdername

1. Using 'strcmp' instead of 'strncmpi' to avoid multi-posID. If my placeholder contains 'P1' and 'P10', 'strncmpi' will give two posIDs.
2. The position of picture placeholder seems to be transformed to six vector like [1, 1, Nan, 5, Nan, 5] when using customized templates, which cause wrong position of picture. Fix this by adding an 'if' sentence.
stefslon/exportToPPTX