Replace "required" and "not required" in all normative text

Global: Replace all usages of "required" or "not required" in normative text. See PI (for a function example) or 6.5 Traditional Complex Number Notation for a more challenging example in prose.

Not correcting all the issues but as an illustration:

"In addition, to meet this capability, all standard infix arithmetic operators for numbers (, , *, /, ^), the comparison operators = and <>, postfix %, and prefix "" and "" shall correctly work with the Complex type (that is, they can accept and generate it, as appropriate), with the exception that they are not required to accept the Text type as equivalent. Thus, the following formula is true: =(2+3i)+(4+5i)=6+8i. All of these operators shall support complex numbers on either or both sides, in addition to Number on either side."

Sorry, comparison (and other operators/functions) operators are not subject to "shall" statements. We are defining those operators/functions and it is on our watch what they do/don't support.

Rather, evaluators that claim to conform to some level of OpenFormula, support the operators/functions as we define them. The burden of making those definitions clear is on us.