[Seaside] Seaside 2.7

[Philippe Marschall]

Hi

Now that Seaside 2.7 is about to be ported to VW and development of
Seaside 2.8 has started I thought I write a mail to summarize Seaside
2.7. The main goal of Seaside 2.7 was that Lukas does not have to tell
anyone to override #rendererClass when he goes to Krakau next week ;)

to sum up Seaside 2.7 brings:
- canvas renderer is default, the old renderer is deprecated
- new, canvas like header api
- file library
- some tools have been cleaned up
- new image map api (see WAScreenshot)
- many new elements including ruby
- #fixCallbackTemps an ugly hack upon an ugly hack that saves memory
- WARequestHandler refactoring
- WAAnchorTag >> #text: has been deprecated
- removed WATagBrush >> #tooltip:
- a deprecation api to make all these deprecations possible
- ability to open a debugger on the rendering stack of an element
- pretty printer fixes and improvements (including comments)
- cookie fixes
- convenience methods in WARequest
- WAListener (comet support)
- more stuff that I forgot about

some of this stuff has been backported to 2.6b1

If you upgrade from 2.6 you need to implement the following method in
all your components that don't use the canvas API

rendererClass
    ^WAHtmlRenderer

additionally after loading the code you need to

WAKom stop; startOn: 8080.
WAComponent allSubclassesDo: [ :each | each initialize ].

Cheers
Philippe