Fix anonymous no-clock analysis screen shift

[jas14]

Closes #1874. It's possible to be looking at an anonymous game with clock info for some nodes but with no clock info for the current node. Setting the player name to   will prevent the screen from shifting between nodes with and without clock info for those games.

This code affects display for all analysis situations, so I've tried to capture all possible scenarios below. The two not listed that I can think of are:

• a non-synthetic anonymous game with no time control, which I don't believe it's possible to create (just tried to do so and was told "you need an account to do that")
• a study with clock info but no player info (don't know if it's possible to have a study with clock info?)

Situation	Picture	Notes
Non-synthetic anonymous game	https://user-images.githubusercontent.com/569991/144712139-0e5d6636-3cdb-4e91-bfd6-d0bef7266b52.mov	No screen jumps when move node has no clock info - this is the new behavior
Study without player info		Player bars not included, as before
Study with player info		Player bars included, as before
Synthetic analysis (no player info)		Player bars not included, as before
Non-synthetic non-anonymous game	https://user-images.githubusercontent.com/569991/144712244-e4540efc-d1e2-4e60-b491-dd83742d716e.mov	No screen jumps, as before

[veloce]

Thanks!

[baack]

Thanks a lot!
Looking forward to get working analysis back in the next release, hope it won't take long.