v1.5.4

What's changed:

• 1090 MHz ADS-B decoder, ADS-B mode and 2d map (issue #160)
• Keep an Icom on simplex across a band change, give SSTV its own FM mode for VHF, and hand the SQL rail to the radio that is doing the squelching (issue #192)
• Report converter overload, and stop a marginal signal inventing the country code that relabels a station RBDS (issue #173)
• Re-select the FDM-S configuration and start its FIFO only once transfers are queued (issue #178)
• Reply in the slot the DX is not transmitting in, whether their slot began on a half second or they were last heard several turns ago (issue #191)
• Mirror the IC-7760's 12 kHz IF so SSB lands on the sideband it was sent on, with an operator override for any radio the model table has wrong (issue #183)
• Teach the LAN Icom model table the menu numbering of every radio that speaks the protocol, starting with the IC-7610 (issue #190)
• Decode xHE-AAC by loading libfdk-aac at run time, and fix the frame borders and output buffer that left it silent (issue #171)
• Serialise every sign-in, ask before adding a radio at a station, hold a drag's retunes to ten a second, and redial a dropped link by itself (issue #188)