lazy-loader breaks compatibility with PyInstaller

[bwoodsend]

The new lazy submodule loader breaks the dependency analysis of PyInstaller. Normally, we'd manually patch this up on PyInstaller's side but, given that pandas_flavours only has two submodules (minus the one which holds the package's version), one imports only pandas and functools, the other imports the first and functools and neither of them do any processing at all on initialisation, what actually is the point in using lazy loading here anyway? Asides from breaking PyInstaller's analysis (and just looking ugly), it screws with IDE completion and static analysis tools.