Reviewed by Richard.

force all floaters to have follows flags = FOLLOWS_NONE and use llfloaterview::reshape logic instead
removed existing follows flags from any floater XUI and deprecated the follows parameter for floaters

Fixed broken resize indicator on Linux viewer window (EXP-1580).

Implemented new requirements from XD: "Profile window should keep last size,
regardless of whether it was own profile or another users'.
If multiple windows open, last one touched is the size we store."

Per Monty's code review, it's dubious practice to have a class in which
certain members are sometimes visible, other times not. If these were virtual
methods, or non-static data members, the error would be obvious -- but even
with static data members and non-virtual methods, it looks like an ODR
violation. Extract conditional methods as free functions, as in changeset
07cd70e75473.