build html doc with lively.persistence.Serializer.documentForWorldSerialization
remove old serialization code
add external and embedded css to html doc
comment
add arbitrary html to html doc
make #saveWorldAs use new document building
extracting doc building into doc builder obj
fixing object migration
removing debugger stmt
using data attributes for morphid and node-type
initializing worlds with documents instead of specific dom elements by default
using "text/x-lively-world" script type for serialized json
bootstrap tests for html and xhtml docs
fixing bootstrap from html doc
proper html preview
ensure that there is only one lively-base-style
ensure that styles are only inserted once (via id attr)
remove debugger stmt
fixing world init with document and dom element
fixing load screen for  html doc