IndexOutOfBoundException for empty commands: metadata, record, run, script

[snuyanzin]

Any of

!metadata
!record
!run
!script

will fail with something similar to

java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
	at java.util.LinkedList.checkElementIndex(LinkedList.java:555)
	at java.util.LinkedList.remove(LinkedList.java:525)
	at sqlline.Commands.metadata(Commands.java:163)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sqlline.ReflectiveCommandHandler.execute(ReflectiveCommandHandler.java:38)
	at sqlline.SqlLine.dispatch(SqlLine.java:791)
	at sqlline.SqlLine.begin(SqlLine.java:668)
	at sqlline.SqlLine.start(SqlLine.java:373)
	at sqlline.SqlLine.main(SqlLine.java:265)

At least it makes sense to have more relevant exception message

[julianhyde]

Fixed in 4bb2ed1, PR #91. Thanks @snuyanzin!