Stop using Icon font for web player

[echarlie]

robot eyes are in the free-use area of Unicode. Apple has assigned church to the "speaker" icon we use, and "house" to the muted speaker icon. it does not conflict with the play button. We should use simple PNGs, as we do not use glyphicons anywhere else.

[mutantmonkey]

Is this currently causing a problem? It's also not true that we don't use glyphicons anywhere else; they are used for the playlists viewer (e.g. the flame/disc icons for new and vinyl, respectively)

[echarlie]

causes an issue when I don't load fonts from the website (e.g. with "content blockers" like firefox focus in iOS safari)

[echarlie]

bootstrap provides an SVG icon set. e.g. https://icons.getbootstrap.com/icons/play-fill/ and https://icons.getbootstrap.com/icons/volume-up-fill/ that we could use, instead