We may as well use this trait now that it’s available!

With the new OptionSet trait, the from_word constructor doesn't really do much by itself.

This cleans up the options module, moving the structs that were *only* in use for the columns view out of it.

The new OptionSet trait is used to add the ‘deduce’ methods that used to be present on the values.

Move to stable

Changes to the way ANSIStrings work mean we need to dereference the strings before putting them in an ANSIString. There's more that can be done here, but this gets it to compile for now.

As of rustc 1.6.0-nightly (1a2eaffb6 2015-10-31), anyway.

This should prove more stable than relying on a Git version.

This warning was 'caused' by the previous commit (but it's small and easy to fix, so don't worry)

Fix integer length error on 32bit environment

this commit fixes below type mismatch error:

```
src/output/details.rs:585:49: 585:60 error: mismatched types:
 expected `i64`,
    found `i32`
(expected i64,
    found i32) [E0308]
src/output/details.rs:585         let date = self.tz.at(LocalDateTime::at(timestamp.0));
                                                                          ^~~~~~~~~~~
src/output/details.rs:585:49: 585:60 help: run `rustc --explain E0308` to see a detailed explanation
error: aborting due to previous error
Could not compile `exa`.
```

- VariableOffset -> TimeZone::VariableOffset

The `unused_results` lint was complaining that the results of inserting into a `MockUsers` object weren't being inspected. These are mock users, so all that would be returned is `None` to indicate that they weren't already in the table -- they're fine to ignore! So, suppress the warnings for those two testing modules.

This makes exa work on other platforms than linux and macosx.

This fixes a bug where an extra header line was printed when in --long --grid mode.