Add day divider

See merge request !272

roomhistory: cleanup references to MessageBox

See merge request !271

This removes clones and refactores how room_history keeps track of
messages.

messagebox: remove MessageContent from MessageBox

See merge request !270

The MessageConetent is removed from the MessageBox, because it is not
really needed there and we should try to not make copies of a Message.
This also makes always use of &MessageConetent instead of some times
cloneing it.

This reverts merge request !268

This reverts merge request !269

uibuilder.rs: Add scroll_widget to uibuilder

See merge request !269

A component previously used in main_window.ui  was moved into
scroll_widget.ui and called from App.ui.builder. However with
the move scroll_widget wasn't added to the rest of the files
in the GtkBuilder used for that call, causing a panic on
startup.

Now uibuilder adds the resource for scroll_widget.ui

Basic Mobile UI

See merge request !268

# Conflicts:
#   fractal-gtk/src/app/connect/mod.rs

roomhistory: create custom widget for scroll view

See merge request !265

Applies a style class, folded-history, whenever the leaflet is
folded. folded-history shrinks the padding around the message
list to 6px from the default 18px.

Sets the slide animation for the HdyLeaflets for a nice
animation when switching between primary and secondary views.

HdyLeaflet is a widget that can be used in split-header apps
like Fractal to split the panes into views, one primary and one
secondary.

This commit splits the main view of Fractal with HdyLeaflet so
at small sizes the room list is the primary view, and the room
history is the secondary view.

roomhistory: remove shown message count

See merge request !267

widgets/message.rs: Ellipsize display names

See merge request !266

We don't need to keep track any more how many messages are shown in the
room history, since we are displaying all locally stored messages

This moves the ScrolledWindow to a custom widget, to clean up code
inside AppOP and decrease its size.

Long display names could resize the window and prevent
the user from shrinking it. Now display names are ellipsized
at the end if there is not enough space to display them.

Related to #351

roomhistory: fix scroll down button

See merge request !264

Since the last changes we have to updated the destination value for the
scrolled animation, else it wouldn't scroll to the end when pressed
while new messages are added.

roomhistory: keep scroll position when adding messeges

See merge request !263

This adjusts the scroll position when more messages are loaded. Also
messages are fetched once the user reaches the edge -2*pageSize.

Log crate

This MR aims to solve (at least part of) issue #354 


See merge request !259

roomhistory: draw messages from the buttom up

See merge request !261

roomhistory: make rendering a message much faster

See merge request !260

center room name on room history, fix  #329

Closes #329

See merge request !258

This attaches the room history to the input field and makes loading of
messages a little bit smoother.