.3y285ra: Fixed the Show All Things/Properties links

Those were too hard-coded, and hadn't kept up with the changes in the
way names are constructed.
Release 0.9.2
Merged add-photos branch
Release 0.10
Tweak to store photos under the Space's ID in S3

Remembered that I had intended to do this, to keep the bucket halfway
manageable.
Release 0.10.1
Took a number of inappropriate Props out of the Add Property menu

Introduced Basic.SystemOnlyProp, which connotes that only Querki itself
can add this Property to a Thing.  (But it is still a public, documented
Property that you can read.)  Applied this to most of the Image Props.

Also marked a few things as Internal that weren't previously.
Added the _photoTarget function

This shows the first picture in a list, and serves as a target for
displaying a thumbnail full-sized.

To help this work, enhanced QLContext to keep track of the Property /
Function that was used to produce a given QValue.  This lets us look
back up the tree, and hook the target and the thumbnails together by the
property from whence they originated.
Removed internal props from the Add Property listing

Turns out to be an old bug -- somewhere along the line, I accidentally
duplicated the Property-filtering code, and the real code wasn't doing
everything I needed it to.  Removed the now-dead code.
Refactored link selection

Merged some duplication between the ordinary LinkType and the rendering
of Optional, pursuant to making Choices work very differently.

Renamed the "Enumerated Category" flag to "Is a Choice", based on
conversation with Anna a month or two ago.  This will eventually feed
into a Choice-building wizard.
Release 0.10.2
Added the go-to-Thing button in Thing Editor

This deals with a workflow problem I've been having for ages: once I've
created a new Thing using the _createButton, I sometimes want to *look*
at that Thing, and there was no good way to do so.  So we now introduce
a button that is specifically for this purpose.
Release 0.10.3
Bugfix: _first now preserves type in empty collections

Previously, if you passed an empty Collection into _first, the result
would be the untyped QNone, which could cause somewhat mysterious
downstream errors from functions expecting a particular Type.  _first
now preserves the PType of the received Collection -- yay, stronger
typing!
Release 0.10.3.1
.3y285wr: made ExactlyOne YesNo property work in the Live Editor

Checkboxes are a weird exception in HTTP.  We'd worked around this in
the old Editor, with the complex "empty" mechanism, but the live editor
is simpler.  Put in a more straightforward workaround.
.3y285th: fix multi-word and messy Tags

We weren't undoing SafeUrl properly, with the result that multi-word
Tags simply weren't clickable.
.3y285tn: photo upload on a third-party page now works right

Previously, if you had page A containing [[Page B -> _edit]], a photo
uploader for Page B would send the photo to Page A.  This is now fixed.
.3y285uc: Status line is now fixed-position

This was a real problem on mobile: if I was scrolled down, I couldn't
tell whether I was done saving, and that matters on a slow 3G
connection.
.3y285xe: The Owner is now listed in SpaceMembership

This was a dumb oversight before, but we'll deal with it now.  Uses the
Evolution mechanism, since there is no structural change required.