0.15.0

• Show containers stats (inspired by Whaler)
• Add GPU usage in Indicator
• Remove transparency from CPU stacked chart
• Add docker icon
• Update Ukrainian translation
• Update Portuguese translation @hugok79
• Update Japanese translation @ryonakano
• Update Russian translation @camellan
• Fix segfaults caused by issue in assigning colors in charts @vjr
• Add an option to choose refresh rate
• Use harmonic mean to calculate frequency values @adm313