Add isns_query_init() and isns_query_pop()

Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>
Invoke isns_rsp_handle() for all responses

Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>
Refactor signal handling to check the return value of read()

Reported by Coverity Scan.

Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>
Improve readibility of event matching conditionals

Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>