re­de­fine – Con­di­tional macro, etc., def­i­ni­tions

De­fines com­mands \newdef, \newgdef and \newlet that warn the user if a com­mand is re­de­fined us­ing them (if op­er­at­ing un­der LaTeX, \new­com­mand is sim­i­larly mod­i­fied). In ad­di­tion \newif, \new­box, \new­count, \newdi­men, \new­toks are mod­i­fied to de­tect an er­ror if a con­di­tional or reg­is­ter name is reused.