building on osx
Merge pull request #14 from arlolra/osx

Add notes about building on OS X.
Add a checkbox to retain inbox messages.

While checked, inbox messages will not be deleted.
Background color for inbox messages near deletion.

This change causes the background color in the listUI (on the left) to
change for inbox messages are are near (gray) deletion or will be
imminently deleted (red).
Delete inbox messages while open.

With this change, inbox messages will be deleted while the client is
open, as opposed to only when the client is restarted, as was previously
the case.
Also delete outbox messages while running.

Similar to the previous patches to delete inbox messages while Pond is
running (as opposed to just when closing), this change deletes outbox
messages during normal operation.
Add command-line utility to decrypt detachments.
Don't attempt to remove invisible messages from UI
Set filename hints for dialogs.

Ubuntu's GTK has a slightly different file dialog that really didn't
work well with the previous code as it didn't get filename hints.
Tidy up some go vet warnings.
Add a package to implement the new ratchet.

This is Trevor Perrin's axolotl ratchet:
https://github.com/trevp/axolotl/wiki

The code isn't wired into anything yet, it just exists and has
tests.
Add option for generated PANDA secrets.

This changes the working in the new contact UI and adds a "Generate"
button in the PANDA flow. This is to support exchanging shared secrets
via email or IM which, while not as secure as other options, is a lot
easier.
Wire in new ratchet system.
Typo fix.

(Thanks to an anonymous contributor for pointing it out.)
Don't mention --state-file on OS X.

OS X sets odd flags when running from the GUI and the flags package
doesn't like it. So main_darwin.go does not use flags, but the error
message still mentioned --state-file.

(Thanks to the anonymous contributor who pointed this out.)
Fix OS X build.
Update documentation.
Remove debug logging from the disk code.
Fix Ubuntu package name
Remove remark about binaries not being available.