Fixes issues with non-atomic writes to IBC files from REPL

While vim is interacting with the Idris REPL over sockets
and we call 'idris --check' we end up with inconsistent IBC
files. Lets us instead call 'idris --client :l' as it is both
consistent with REPL interactive workflow and faster.

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>