Parse the contents of the "pg_basebackup_options" parameter in repmgr.conf

This is to ensure that when repmgr executes pg_basebackup it doesn't
add any options which would conflict with user-supplied options.

This is related to GitHub #206, where the -S/--slot option has been
added for 9.6 - it's important to check this doesn't conflict with
-X/--xlog-method.

While we're at it, rename the ErrorList handling code to ItemList
etc. so we can use it for generic non-error-related lists.

dbutils.c

@@ -1,5 +1,6 @@
 /*
  * dbutils.c - Database connection/management functions
+ *
  * Copyright (C) 2ndQuadrant, 2010-2016
  *
  * This program is free software: you can redistribute it and/or modify