pdn_aprs 1.0.1

Refusals carry a reason code.

• A refusal now says why in a form a program can act on: pdn_aprs_encoded gains int refusal at the end (a pdn_aprs_refusal code, zero for none and for every error that is not PDN_APRS_ERR_REFUSED), and pdn_aprs_refusal_name() gives the vectors' kebab-case id. The 26 codes are the refusal ids of the shared vectors; new ones may be appended in a later 1.x release, so keep a default case. Build calls fill it in result too. The message text is unchanged and still not stable API.
• Fixed: a header address the encoder cannot write (pdn_aprs_encode_tnc2 and pdn_aprs_encode_ax25) returned PDN_APRS_ERR_ARGUMENT, though the header documents PDN_APRS_ERR_REFUSED. It is now PDN_APRS_ERR_REFUSED with PDN_APRS_REFUSAL_INVALID_ADDRESS (TNC2) or PDN_APRS_REFUSAL_AX25_CANNOT_CARRY (AX.25) and a reason. NULL pointers stay PDN_APRS_ERR_ARGUMENT.
• An altitude given to pdn_aprs_build_mic_e in feet and in metres is now PDN_APRS_ERR_REFUSED with PDN_APRS_REFUSAL_VALUE_GIVEN_TWICE, where it was PDN_APRS_ERR_ARGUMENT.
• When data breaks several rules the refusal names the first by the shared order of the vectors' DESIGN.md (a fault in a field on its own before one about how fields relate; the header before the data).
• An address written with SSID -0 (N0ZO-0) is now refused by pdn_aprs_encode_ax25() and pdn_aprs_write_ax25() with PDN_APRS_REFUSAL_AX25_CANNOT_CARRY, like WB4APR-00, since a frame gives it back as N0ZO. This holds for a third-party inner header too. It was written with no SSID.
• The dump tool writes refusal (encode and build), reencode_refusal (decode) and ax25_refusal (the API view) in its records.