Add .shellcheckrc to silence lints

.shellcheckrc

@@ -0,0 +1,8 @@
+# Many array expressions are constructed and eval-ed
+disable=SC2016
+# False positive on "CMDARG_ERROR_BEHAVIOR=return"
+disable=SC2209
+# Checking exit code with $? is more of a preference when the script doesn't try to support the errexit shell option
+disable=SC2181
+# Masking exit codes isn't much of a problem in this script
+disable=SC2155