Fixes #18

[Dunbaratu]

This has been sitting a long time, but was stuck on not
liking any syntax choice - then it came up in Discord
again and people seemed to like this, so I finally did
it:

CHOOSE expr1 IF bool_expr ELSE expr2.

[teleksterling]

Suggested change

	+
	+print "Third nesting case - nesting choose in the first term.".
	+print " Next two lines should be 'A'.".
	+print " " + (choose (choose "A" if true else "B") if true else "C").
	+print " " + (choose choose "A" if true else "B" if true else "C"). // same without parens should work.
	+print " Next two lines should be 'B'.".
	+print " " + (choose (choose "A" if false else "B") if true else "C").
	+print " " + (choose choose "A" if false else "B" if true else "C"). // same without parens should work.
	+print " Next four lines should be 'C'.".
	+print " " + (choose (choose "A" if true else "B") if false else "C").
	+print " " + (choose choose "A" if true else "B" if false else "C"). // same without parens should work.
	+print " " + (choose (choose "A" if false else "B") if false else "C"). // result of inner test should affect result
	+print " " + (choose choose "A" if false else "B" if false else "C"). // same without parens should work.
	+
	+