write: discard calls setDom which in turn wipes all dynamic content

[kapouer]

Affected elements:

• fetch
• include
• sitemap

[kapouer]

That's fixed in 8a181a095639e21082f79203a554401cb892fdea and d9de4827ce1c4c1b954bbf1f758bfbf051a64c2b and 7b58022d1a6ddb9b8e5fd9f01806d9968934c728.

It was tricky because i realized only too late that it was a "three states" problem:

• db state
• parsed state
• unsaved state

Now the editor doesn't remove html content, even if virtual, and the store does remove virtual content and empty content objects.