Fix expand_cr behavior with 'smartindent'

When indentation is controlled by 'smartindent', the expand_cr behavior
doesn't end up producing the same results that you would get without
delimitMate. The following behavior results instead:

Before: {|}
After: {
		|
	}

The expected behavior is to produce the following:

Before: {|}
After: {
	|
}

To that end, detect when indentation is controlled by 'smartindent' and
adjust the indentation of the close line to match.