Store original position of text box

This stores the original x-position and y-position of the text box, and
when a text box gets repositioned, it will use those unless a crewmate
position overrides it.

This is the original position of the text box, before centering or
crewmate position is considered.

This fixes a bug where a cutscene text box can be "shifted" from its
normal position via CTRL+F8 cycling if there is a translation that is
too long for the screen and thus gets pushed by adjust(). I tested this
with the text box in the Comms Relay cutscene that starts with "If YOU
can find a teleporter".

This is not applicable to function-based translations
(TEXTTRANSLATE_FUNCTION), because the responsibility of correctly
positioning the text box resides with the function.

desktop_version/src/Script.cpp

@@ -773,6 +773,8 @@ void scriptclass::run(void)
                 context.text_case = textcase;
                 context.lines = std::vector<std::string>(txt);
                 context.script_name = scriptname;
+                context.x = textx;
+                context.y = texty;
 
                 graphics.textboxcrewmateposition(&textcrewmateposition);
                 graphics.textboxoriginalcontext(&context);