[MLton] replaced tabs by spaces in source files

[Matthew Fluet]

> Some files with tabs were not changed, in particular, regression
> output, .st files (Matthew, what about these?), Makefiles, patches
> that include Makefiles require tabs.  Here's a complete list of
> (ASCII) files that still have tabs in them.
>
> ide/enscript/sml_verbose.st
> ide/enscript/sml_fancy.st
> ide/enscript/sml_all.st
> ide/enscript/sml_gaudy.st

These do not need tabs; I've run expand on them and committed.  You can 
add them to the svn commit hook if you like.