Disable shellcheck on sourced scripts

Turns off shellcheck parsing sourced scripts and removes some shellcheck
directives that are no longer necessary.

.shellcheckrc

@@ -1,7 +1,7 @@
 # Global settings for Spellcheck (https://github.com/koalaman/shellcheck)
 enable=all
 
+external-sources=false
+
 # Disable variable referenced but not assigned
 disable=SC2154
-
-

jobs/JGLOBAL_ATMOS_POST

@@ -1,6 +1,5 @@
 #! /usr/bin/env bash
 
-# shellcheck source=ush/preamble.sh
 source "${HOMEgfs}/ush/preamble.sh"
 
 export RUN_ENVIR=${RUN_ENVIR:-"nco"}
@@ -12,7 +11,6 @@ configs="base post"
 export EXPDIR=${EXPDIR:-${HOMEgfs}/parm/config}
 config_path=${EXPDIR:-${PACKAGEROOT}/gfs.${gfs_ver}/parm/config}
 for config in ${configs}; do
-    # shellcheck source-path=parm/config
     . "${config_path}/config.${config}"
     status=$?
     (( status != 0 )) && exit "${status}"
@@ -22,7 +20,6 @@ done
 ##########################################
 # Source machine runtime environment
 ##########################################
-# shellcheck source-path=env
 . "${HOMEgfs}/env/${machine}.env" post
 status=$?
 (( status != 0 )) && exit "${status}"
@@ -43,9 +40,7 @@ cd "${DATA}" || exit 1
 ##############################################
 export cycle="t${cyc}z"
 setpdy.sh
-# shellcheck disable=SC1091
 . ./PDY
-# shellcheck disable=
 
 
 ##############################################

scripts/exgdas_atmos_post.sh

@@ -24,7 +24,6 @@
 # echo "-----------------------------------------------------"
 #####################################################################
 
-# shellcheck source=ush/preamble.sh
 source "${HOMEgfs}/ush/preamble.sh"
 
 cd "${DATA}" || exit 1

ush/gfs_post.sh

@@ -214,6 +214,7 @@ export POSTGPEXEC=${POSTGPEXEC:-${EXECgfs}/upp.x}
 export OVERPARMEXEC=${OVERPARMEXEC:-${EXECgfs}/overparm_grib}
 export POSTGPLIST=${POSTGPLIST:-/dev/null}
 export INISCRIPT=${INISCRIPT:-}
+# Ignore warning about single quote not subtituting now
 # shellcheck disable=SC2016
 export ERRSCRIPT=${ERRSCRIPT:-'eval (( err == 0 ))'}
 # shellcheck disable=