Use Vector drawables instead of pngs or jpgs

[PiSolve]

• our app uses a lot of icons and resources , soon it will outgrow the required app size.
  We should rather use vector drawables.
  https://www.paintcodeapp.com/
  Can be used to create vector drawables.

[arynchoong]

There's a tradeoff, vector drawables are heavy on processing. Lollipop (API 21) does not support SVG, not without heavy compatibility support.
All the icons used thus far are from Google's material icon, they have SVG format for icons used.