Add net spending/income pie charts (fixes #657);

4 jobs for grouped-pie-charts in 11 minutes and 31 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Lint
passed lint #309505

00:03:16

 
  Build
passed build #309506

00:03:27

 
  Test
passed lint_history #309508

00:04:02

passed test #309507

00:04:47