Rewrote Int.fmt to eliminate allocation overhead.  Previously this constructed a list of characters and then concatenated.  This was made worse by 1076 since quotrem currently returns a pair on the heap resulting in 6 words of heap for each character.  In some Isabelle examples Int.toChars was the largest allocator.
Rewrote Int.fmt to eliminate allocation overhead.  Previously this constructed a list of characters and then concatenated.  This was made worse by 1076 since quotrem currently returns a pair on the heap resulting in 6 words of heap for each character.  In some Isabelle examples Int.toChars was the largest allocator.

git-svn-id: 98787b36aaefbae4b30fa755be920954cd25e1e4@1115 ae7d391e-3f74-4a2b-a0db-a8776840fd2a

dcjm/polyml,dcjm/polyml,dcjm/polyml,mn200/polyml,polyml/polyml,mn200/polyml,dcjm/polyml,mn200/polyml,polyml/polyml,mn200/polyml,polyml/polyml,polyml/polyml