[RCD] New look of compose and message screens

In last few changes I improved message display screen. So, now it looks the same as the preview frame. I think this way the UI looks more clean and unified. I hope you agree with me. This also matches the look of other tasks e.g. addressbook where white color is used for the whole contact information frame/box.

Because I was never happy with that how mail compose screen looks like, the idea came to make the same with compose screen. I started to work on this. See attached screenshot. The main reason of this change is a unification, but it will fix some issues on compose screen. E.g. the whole compose box will be scrollable so there will be no problems with too small screen height (even with displayed all headers and options).

Opinions?