Shellcheck v0.6.0 and style compliance changes.
Fixed minor bugs related to capturing output, driven by
shellcheck changes.
Fixed sync_replica.sh for standby replicas with the
configurable rpl.journalcopy.location=1 (SDP-424),
removing an unnecessary and broken check.
Fixed test for pre-existing checkpoints in function
recreate_offline_db_files() so that it checks only
for the master server, fixing an issue where it would
report "No checkpoints found - run live_checkpoint.sh"
when used on a replica where checkpoints might
legatimately not exist. Also fixed the actual test itself.
Replaced P4COMMITSERVER variable with P4MASTERPORT to
support daisy chain scenarios, removing the assumption
that all servers target only the master. (This assumption
was made only in journal_watch.sh).
Enhanced check_vars() to report individual missing
environment variables, and to add more info on how
to fix environment problems (e.g. adding to
p4_vars or p4_N.vars files).
Fixed bug in check_dirs() where a missing directory check
intended to result in a die() call would result in a
syntax error instead.