make it possible to define lines in licenseFileOverrides

[mojoaxel]

We needed to define some license-file mappings in the [licenseFileOverrides option] because some (old version) of some libs had their license statement not inside a seperate file, but in the README.

So we needed to set something like this:

licenseFileOverrides: {
	'cookie-signature': 'Readme.md',
	isarray: 'README.md',
}

This results in the (whole) README to be used as license text.

It would be better is we could define some lines inside a file and only use these lines as the license text.
We would try to provide an implementation for that over the next weeks.

Please vote on the implementation details:

[mojoaxel]

We propose this way to implement this:

licenseFileOverrides: {
	'cookie-signature': 'Readme.md/#L21-L42',
	isarray: 'README.md#L40-L60',
}

[mojoaxel]

Alternatively we could make it more verbose:

licenseFileOverrides: {
	'cookie-signature': {
		file: 'Readme.md',
		lines: {
			from: 21,
			to: 42 // optional
		}
	}
}