Add reverse route / delete last point buttons

[bagage]

Fixes #54
Fixes #33

[nrenner]

No sure we should use the undo icon (fa-undo) for something that isn't really an undo function, maybe one day we get around actually implementing a proper undo feature.

Maybe something like fa-long-arrow-left stacked with fa-map-marker instead?

[bagage]

I started to replace undo icon but currently it does not look OK:

I'm not sure how we can stack then vertically, if you have an idea feel free to modify this MR directly :).

[nrenner]

It gets horizontally aligned without fa-lg, and I moved the marker with margin and colored it gray so they're better distinguishable, but I still don't like it:

'<span class="fa-stack"><i class="fa fa-map-marker fa-stack-1x" style="margin: -2px 0 0 2px; color: gray;"></i><i class="fa fa-long-arrow-left fa-stack-1x"></i></span>',

I guess this one is better? Marker gray to indicate fading and to highlight left caret as back/backspace.

'<span><i class="fa fa-caret-left"></i><i class="fa fa-map-marker" style="margin-left: 1px; color: gray;"></i></span>',

[bagage]

Yes last one is looking good IMHO.