This method is intended to elegantly subsume two common iteration functions.
The first is `iter::range`, which is used identically to the method introduced
in this commit, but currently works only on uints. The second is a common case
of `{int, i8, uint, etc.}::range`, in the case where the inductive variable is
ignored. Compare the usage of the three:
```
for iter::range(100u) {
// do whatever
}
for int::range(0, 100) |_i| {
// do whatever
}
for 100.times {
// do whatever
}
```
I feel that the latter reads much more nicely than the first two approaches,
and unlike the first two the new method allows the user to ignore the specific
type of the number (ineed, if we're throwing away the inductive variable, who
cares what type it is?). A minor benefit is that this new method will be
somewhat familiar to users of Ruby, from which we borrow the name "times".
Each numeric type now contains an extensions module that is automatically
exported. At the moment each extensions module contains only the impl for the
`num::num` iface. Other impls soon to follow (hopefully).
Fixing a FIXME turned out to be pretty involved. I added an io function
that returns a unique boxed string (for the contents of a file) rather than
a string, and went from there. Also made the src field of codemap a unique
boxed string. This doesn't seem to make that much difference in amount of
allocation according to valgrind (disappointingly), but I also had to introduce
a copy somewhere else pending a new snapshot, so maybe that's it.
Now that core exports "option" as a synonym for option::t, search-and-
replace option::t with option.
The only place that still refers to option::t are the modules in libcore
that use option, because fixing this requires a new snapshot
(forthcoming).
