Icon aliases cleanup

[Pedro Neves]

On 30-11-2017 12:02, Martin Měřinský wrote:
> Hello,
> I'm working towards icons code cleanup and the possibility to create
> other, nicer, scalable icons. Possibility to change icons in Subsurface
> at will. And finaly usage of your current GUI icons in Subsurface,
> where meaningfull.
>

Hi Martin:

It seems a good idea. In fact, while looking as our icon set (the ones 
in subsurface/icons/) we seem to have a repeated one: warning.svg and 
warning-icon.svg.
Also (and probably there's an obvious reason for it, that I don't know), 
why do we keep svg and png versions of the same icons?

Cheers:

Pedro