Support web searches for current word

[yehia2amer]

Issue Description: Add a feature to open the web browser to lookup the current word on the user’s chosen reference site. For example, if the user has chosen Word Reference searches in English and the current word is “Java" then the browser would open on the page https://www.wordreference.com/definition/java. This would be achieved by inserting the current word into the URL of the form https://www.wordreference.com/definition/${word}. We will need a way to allow the user to select their reference website of choice, perhaps from a pre-defined list of options.

As Discussed with @AdamCarroll in #41