New server-call: get_last_text.

src/server/cache.h

src/server/call-switch.awk

src/server/connections.h

src/server/fncdef.txt

src/server/internal-connections.c

src/server/prot-a-output.c

src/server/prot-a-parse-arg-c.awk

src/server/prot-a.c

src/server/simple-cache.c

src/server/text.c