Interface: start GameControl sooner

this has a minor (and brief) graphical glitch that im not in the mood to hunt down
LoadScreen: append the "hint" to the message TA
DisplayMessage: repurpose DisplayString

DisplayString(String&, Scriptable* = NULL) -> DisplayMarkupString(String&)
the few cases of non-markup can be handled in the other dispatch methods

putting in some asserts so that I can verify :p