* scd/apdu.c (pcsc): New variable.
(struct reader_table_s): Remove pcsc.context from member.
(pcsc_get_status, connect_pcsc_card): Use pcsc.context.
(close_pcsc_reader): Release pcsc.context here with reference count.
(apdu_open_one_reader): Move API loading to ...
(pcsc_init): new.
(apdu_open_one_reader): Remove.
(apdu_open_reader): Call open_pcsc_reader instead of
apdu_open_one_reader.
(open_pcsc_reader): Call pcsc_init if needed.  Call close_pcsc_reader
instead of pcsc_release_context.  Make reader parsing more robust.
(apdu_init): Initialize pcsc.count and pcsc.context.