2020-06-08: v1.90.4 release

This release contains a number of important bugfixes. On the feature side, the USB hotplug support was improved. A lot of drivers received fixes and improvements.

Highlights:

• Work around GUsb cancellation issue
• Redefine internal image device state machine for more robustness
• Add public finger-status reporting to FpDevice
• Rework device removal API to be convenient (#330)
• Enable powersave for unsupported USB devices
• Improvements to examples
• synaptics: Support identify operation
• synaptics: Fix possible crash when the interrupt transfer is resubmitted
• synaptics: Add support for PIDs 0x00f9, 0x00fc and 0x00c2
• elan: Add PID 0x0c4d to supported device list
• aes3k: Fix driver and add CI test (#306)
• uru4000: Fix reference counting of image transfer
• vfs301: Fix driver and add CI test (#320)