ComputeVariance in NdrConformantVaryingStructBufferSize.

that we can parse the towers received from native rpcrt4.

by passing the correct type format string to ReadConformance.

Add tests for name values, and move tests for different string
encodings to there.

Add some tests for these undocumented functions.

rpcrt4: Add functions for generating and parsing the upper floors in endpoint-mapper towers for different transports.

- Open large popup menus on the other side only if there's enough space
- Open popup menus such that the y position of the first item in the
  popup menu is the same as the y position of the focused menu item.

Replace all 'while (PeekMessage()) DispatchMessage();' loops in the
PeekMessage test by explicit calls to PeekMessage(), check queue
status and processed messages after each call to see what is going on
behind the scene.