Message 350001 - Python tracker

I think that using tabs for Shell indents is IDLE's current worst design wart.  But I agree with KBK (#1196946) that merely replacing tabs with spaces does not really solve the problem, which is the jagged physical margin consequent on physically indenting only the first line with a prompt. 

#37892 proposes to stop using tabs by implementing updated versions of the alternate fixes, 3 and 1, mentioned in msg151418 below. The alternate proposal will fix some other issues as well.