Release v0.8.1

Bugfix

• Was broken on GNU Linux due to reliance on which -s,
  which is a BSDism

0.7.0

• New time-line utility to visualise events over time
• Better resolution of the map behind the heat-map
• Extracted common functionality from all utilities
• Adding command line parameters
  • font size
  • target bitmap dimenstions
  • transparency of graph