v1.4.0

ControlSystems v1.4.0

Diff since v1.3.0

Merged pull requests:

• add loopshapingPID (#732) (@baggepinnen)
• improve robustness in loopshapingPID (#733) (@baggepinnen)
• Broadcasted multiplication bugfix (#734) (@baggepinnen)
• fix poles for static statespace (#735) (@baggepinnen)
• add filter options in loopshapingPID (#736) (@baggepinnen)