-LLCached[COA]Control can now be static const. Use for readonly access.

-const'd all readonly LLCached[COA]Controls to prevent altering by mistake.
-added get() accessor to LLCached[COA]Controls to return cached type explicitly without manual casts.
-added missing operators to LLCachedCOAControl
-Converted a few more settings to LLCached[COA]Control
-Fixed LLColor4U -> LLSD -> LLColor4 problems in LLCachedControl

Ascent functionality fixes:
-Tag coloring pulled out of getClientInfo(Redundant. idleUpdateNameTag already handled it)
--Tag and color substituted at render-time. Simple boolean logic. Neglible perf penalty.
-Fixed llinfos spam if AscentShowSelfTagColor = false
-Client tag updated less superfluously

indra/newview/llviewercontrol.h

@@ -54,7 +54,7 @@ extern std::map<std::string, LLControlGroup*> gSettings;
 void create_graphics_group(LLControlGroup& group);
 
 // saved at end of session
-extern LLControlGroup *gCOASavedSettings;
+// gSavedSettings and gCOASavedSettings moved to llcontrol.h
 extern LLControlGroup gSavedPerAccountSettings;
 
 // Read-only