[Etoys] Some recent big changes

[Yoshiki Ohshima]

  Hello,

  We've been kept relatively quiet, but behind the scene, a lot of new
things (related to Etoys classic) were experimented.  We decided to go
ahead and push some of them to the OLPC image.  Please fetch update
into your image.  I'll make a pre-loaded images shortly.

  The biggest user visible change is that the precedence of operators
in a tile expression now follows the conventional mathematical way;
i.e., multiplication and division is stronger than addition and
subtraction, etc.  Whenever you extend the expression with right
arrow, or change the operator in between terms, a path in the
compilation processes it and produces the "right" result.  This is a
big change and presumably break existing contents; however, without
this, millions of users will suffer.  So we figured that we have to do
this.

  Internally, there is a lot of changes.  Especially the new way of
storing a project is getting ready there.  To be a bit conservative, a
project is stored in the same way as before, but once you evaluate an
expression in a Workspace or TextMorph:

  Project publishInSexp: true.

The new format will be used.  This new format still lets you store
most of Etoys; one thing known to break are when you disassemble a
scriptor's buttons to do certain stuff, it will not work (the
ScriptEditorMorph instance is totally re-created from scratch upon
loading and it doesn't deal with that kind of anomally.)  Please try
it with your projects and let me know how it goes.  Kedama is also in
transition.  Existing projects generally work, but the internal
structure has changed and they should be re-done from scratch for
better compatibility.

  There is a little parser-generator in the system, BTW.  You can
write production rules in the system browser and define a new language
with it.  A Logo-like language that controls Etoys objects would be
nice to have.  If you're interested in such a thing please let me
know, too.

  Thank you!

-- Yoshiki