Comment and shuffle around main.cpp.
Expand out name of player variable.
More stylistic changes to main.cpp.
Use chrono for timestamps.

This is very verbose and requires some hoop jumping, but is
somewhat more clear in its intent (and allows templates for
easily implementing 'seek X seconds').  Is it worth it?
Probably not.  Who knows.

Also, the seek timer is now marked as dirty whenever a new song
is loaded, a new seek is done, and on startup.