Also misc cleanup:
- reorder members to be more consistent and fit the style guide
- remove use of _Pair
- made Variable.applyUpdate and Variable.owner public
- added docs to Priority, tweaked the code a bit
- added some docs to Result
- removed the internal-error Result (replaced with asserts)
- removed unused Results
- made Result const
- merged some files together since they had used privates a lot
I'm sorry this is completely unreviewable. I did the move from `lib/*`
to `lib/src/*` first, then did the `part`-to-`import` change, and then
found out how many of the files involved privates, which I wasn't
expecting. I can redo this as multiple commits if that would make it
easier to review.
Now we just have one TextSpan class that handles both simple strings, trees of
children, and styling both. This approach simplifies the interface for most
clients.
This patch also removes StyledText, which was weakly typed and tricky to use
correctly. The replacement is RichText, which is strongly typed and uses
TextSpan.
This patch makes it easier to use the auto layout API:
* We no longer use operator== because that requires an ugly cast by the
API user.
* Also, "leftEdge" is now just "left" for less verbosity.
* AutoLayoutChild not implies its key from the AutoLayoutParam object.
* We now correctly layout every child of a RenderAutoLayout object even
if the solver doesn't flush any updates to that child.
This patch teaches the widget framework how to use Cassowary-based
autolayout. To integrate autolayout with widgets, I had to refactor how
RenderAutoLayout worked a bit. Now RenderAutoLayout follows the same
delegate pattern we use for custom paint and custom layout.
Previously, hello_world.dart was an interactive circle. I've moved that
to touch_input.dart. We should eventually harmonize the touch input
examples at all the layers.
