std.format.doFormat and std.format.formattedWrite

[Stewart Gordon]

There are several bug reports along the lines of std.stdio.writef* and std.string.format 
and stream writef* functions behaving inconsistently with each other.

So far I've found:

http://d.puremagic.com/issues/show_bug.cgi?id=4532
http://d.puremagic.com/issues/show_bug.cgi?id=5687
http://d.puremagic.com/issues/show_bug.cgi?id=6595
http://d.puremagic.com/issues/show_bug.cgi?id=7571
http://d.puremagic.com/issues/show_bug.cgi?id=7620

Really, they're all one bug, namely the use of two divergent functions that have the same 
purpose: doFormat and formattedWrite.

Under D1, we had only doFormat.  In D2, formattedWrite has superseded doFormat; 
nonetheless, some bits of Phobos are still using doFormat.

6595 is "std.string.format() and sformat() are obsolete".  It seems to be advocating 
killing doFormat once and for all.  However, the pull request doesn't go anywhere near 
this far, and there is even a call to doFormat in the unchanged lines of the pull. 
Really, it only makes sense to get the migration from doFormat to formattedWrite finished 
once and for all.

But meanwhile, what to do with these duplicate bug reports?  Change the summary 4532 to 
reflect the true nature of the problem and then dupe the others to it?  Or open a new bug 
report that is straight and to the point about it, and dupe those to it?  Or list the old 
bugs as dependencies rather than dupes of the new root cause bug?

(Example from years ago of manifestations of a bug being done as dependencies:
https://bugzilla.mozilla.org/show_bug.cgi?id=57724
)

Stewart.