Add inplace editing

[rawdog71]

Add inplace editing for the preview of a page.

At first stage simple datatypes should be editable:

• string
• integer
• real
• text
• datetime
• boolean
• media ?

[rawdog71]

The content part will be dynamically surrounded by a special div.
This div looks like <div cf_inplace="classname:contentname:attributename:attributetype">

• classname is the name of the content class
• contentname is the name of the current selected content
• attributename is the selected fieldname of the class
• attributetype is the selected type (string, boolean, integer, real, ...)

With this information it is possible to fetch and update the value of the content with GetContent and updatecontent.