allow xpathenhancers to match multiple xpaths and combine them in the result

This is useful for example for certain comic sites where you would like to show both the comic and the text accompanying it.

Example json configuration:
```json
"thegamercat.com": {
	"%thegamercat.com%": [
		"//div[@id=\"comic\"]",
		"//div[@class=\"post-content\"]/div[@class=\"entry\"]/p"
	]
}
```

cc @Raydiation