Release v2.2.0

Yet another minor release with accumulated fixes and enhancements. Notable
changes since last release include,

Enhancements:

• pd: add method to flush event queue
• Enable REPLY_ISTATR and REPLY_OSTATR support
• libosdp: Added opaque argument to command_complete_callback
• pytest: Add events tests
• phy: Only flush channel on errors in osdp_phy_state_reset
• phy: Don't attempt to send a NACK for some early failures
• libosdp: Make osdp_cmd_mfg and osdp_mfgrep identical
• cp: Do not propagate PHY errors as-is
• libosdp: Add a ring buffer to store the RX data
• libosdp: Move channel read/writes into phy layer
• unit-tests: Resurrect the old unit-tests modules
• libosdp: Add a softname for PDs in the info struct
• Avoid one ifdef by reorg and static inline-ing
• libosdp: Add support for I/O status monitoring/reporting
• Enable address sanitizer enabled builds

Fixes:

• libosdp: Fix CMD_ABORT's assigned command code
• cp: Fix cardread and keypress event decode cases
• unit-tests: Add a test case to validate the mark-byte skip
• pytest: Fix is_sc_active() to return boolean
• fixup: libosdp: Add support for I/O status monitoring/reporting
• Fix build failure
• Fix OSDP_QUEUE_SLAB_SIZE defintion and some typos
• Fix a heap-buffer-overflow in __cp_setup()