VirtualTally improvements, minor expressions fixes

[pzinn]

• added Number*VirtualTally, VirtualTally == VirtualTally. took this opportunity to optimize VirtualTally ? VirtualTally.
• various minor fixes to expressions, e.g., this used to happen due to an annoying inheritance conflict:

i29 : debug Core

i30 : expression 3*ONE

o30 = 3

o30 : Expression of class Holder

i31 : 3*expression 2*ONE

o31 = 3*2*1

o31 : Expression of class Product

now o31 = 3*2

[mikestillman]

@pzinn Could you merge in development into your open pull requests? This should hopefully fix the errors occuring in github actions.