Renaming Script Contexts

- Determined how the various script contexts were used and renamed accordingly.
- ScriptContext2_Enable/Disable => Lock/UnlockPlayerFieldControls - The sole purpose of the flag is to make sure the player can't move around in the overworld. It has nothing to do with script contexts.
- ScriptContext1 => ScriptContext - It is the global script context used to set up scripts which run over many frames.
- ScriptContext2_RunNewScript => RunScriptImmediately - ScriptContext2's sole purpose was to run scripts immediately and in a separate context, usually while the global context is waiting for things like map loads or screen changes.

src/mystery_event_script.c

@@ -220,7 +220,7 @@ bool8 MEScrCmd_setmsg(struct ScriptContext *ctx)
 bool8 MEScrCmd_runscript(struct ScriptContext *ctx)
 {
     u8 *script = (u8 *)(ScriptReadWord(ctx) - ctx->mOffset + ctx->mScriptBase);
-    ScriptContext2_RunNewScript(script);
+    RunScriptImmediately(script);
     return FALSE;
 }