v0.6.4

Trixi v0.6.4

Diff since v0.6.3

Merged pull requests:

• Make error norm calculation optional (#1755) (@DanielDoehring)
• Make error message for unknown boundary name more helpful (#1762) (@efaulhaber)
• bump lower compat bound of TimerOutputs.jl to v0.5.7 (#1772) (@ranocha)

Closed issues:

• T8code Trixi Trixi2Vtk failed to precompile (#1769)