EHTMLEditor - Avoid asking for loosing the formatting if replying from a selection

Add a special header to the newly created message from the selection
text and later mark the flag in EHTMLEditorView to avoid showing the
dialog for loosing the formatting. Do something similar for messages
from drafts to avoid searching for string inside the message's source.
EHTMLEditor - Rework how the message text, signature and block with initial input are handled when opening composer
EHTMLEditorView - Avoid double citation marks in plain text mode

Mark quoted plain text citations as quoted.
EHTMLEditorSelection - Block format combo box shows wrong format after unblocking the selection-changed signal callback

Reload the properties when unblocking the selection-changed signal
callback.
EHTMLEditorSelection - Correctly wrap long anchors that are on the beginning of the line in plain text mode

We have to insert the BR that is used for wrapping after the link and
not before it.
EHTMLEditorSelection - Fix change of a block format to another one when the citation is selected