Lua function GetLocalMousePosition() change

This function used to return the position of the mouse cursor when it was clicked (for a few frames after the button was pressed) instead of the mouse-cursors current function.

Since this is quite inconsistent and doesn't fit with the function name, this was changed. The function consistently returns the current mouse-position now regardless of whether the LMB was pressed or not.

It's expected to be not a notable change by the user. Feel free to add an issue to the bugtracker or get in touch on the Forum, if this change breaks any of your current use cases.