Update components to fontawesome 4.1.0
Port to fontawesome4
fontawesome-4 renamed font folder to fonts
update fa-font-path less variable
fab css
Port more icons to fontawesome-4
fix some font-awesoem 4 icons
adding options explicitly
Merge pull request #6215 from nzjrs/gtk3-support

add gtk3 support to ipython kernel
allow splitting and merging of heading cells

I consider it a bug that you couldn't merge with heading cells, and that
you couldn't split them, either. (So much so that I thought it was a bug
in ipython-vimception when I ran into it).

This change removes that limitation, so heading cells are on par with
the other cells in terms of the kinds of manipulations one can carry out
with them.
Merge pull request #6126 from takluyver/kernelspecs-nb-ui

UI for changing kernels in the notebook
Merge pull request #6084 from tomspur/fontawesome4

Update fontawesome to 4.1
Remove $el_to_style from the widget javascript code; '' now defaults to this.$el

This seems to make it easiest to select the top-level element.  An alternative is to use special syntax for top-level elements, like in https://github.com/ipython/ipython/pull/6185

This will be followed up by other fixes that let the user set specific common properties of different elements.

This change also adds the .addBack() call, which means that nonempty selectors now apply to this.$el and its descendants, rather than just the descendants of this.$el.
a few todo
Transfer of border-box-sizing from js to css

`border-box-sizing` is pure styling, it has nothing to do in Javascript
it should be put in css to be overwritable.
move border-box-sizing from js to css

nothing to do in js, pure styling.
movestyling from js to css
remove js styling, already done in css + deprecate warning
move styling from js to css
remove js styling, already done in css in logoutmain