Excel can copy huge metafiles to the clipboard, with over 3 million of
actions, which are 1) unusable, and 2) crash LibreOffice because of their
size.

So let's just limit the size of metafiles to be under 100000 actions,
otherwise use the 'OLE' bitmap.

Change-Id: I6a50471e6fe6ab9417592c011bf78cad6247236b