EComposerPrivate: Fix caret position in "Start typing at the bottom on replying"
Composer should know if it was started with new message
Fix combinations of "start_bottom" and "top_signature" composer settings
Fix various bugs in plain text citation quoting
EEditorSelection: Fix detection of citation

With this commit the situation when Enter is pressed in citation (to break
citation) is fixed
Bug #708731 - [webkit-composer] Cannot set signature to none on re-edit
Let the citation text have the same color as in preview (light grey)