Add initial cable and calculator probing code.

Signed-off-by: Lionel Debroux <lionel_debroux@yahoo.fr>
Tentatively add type IDs for .hpappnote and .hpappprgm, so that beta-testers can play with them, and confirm or infirm.

Signed-off-by: Lionel Debroux <lionel_debroux@yahoo.fr>
WIP BROKEN Add cables for Prime and 39gII emulators (doesn't exit properly); add broken cable for 39gII HID; refactor and add APIs.

TODO fix virtual cable flushing / closing !

Signed-off-by: Lionel Debroux <lionel_debroux@yahoo.fr>