reinstate timer on ScreenSelectColor
handle "No NoteSkin Set" crash

The possibility for this crash was brought to my attention recently by a friend who had done a fresh install of SM5 beta4a.  With a fresh install, it seems that the line DefaultModifiers= in Preferences.ini is blank, by default.

Normally, this is fine; no DefaultModifiers are required and the default NoteSkin is used with 1x Overhead.

My recent commits to undo Song-applied modifiers (from 3.95 "gimmick charts") did cause a problem, however, if no default NoteSkin was set. Despite my calling GetPlayerOptionsString() and storing/re-applying the result before and after each song, SM would complain about a NoteSkin not being set and eventually crash.

This commit introduces a somewhat hackish, but seemingly stable, themeside workaround.

I feel like SM should *probably* either:
+ fallback on "default" NoteSkin if none is set, or
+ change GetPlayerOptionsString() to include the current NoteSkin