[SteemSQL Wrapper] Export to Excel, CSV, and JSON

In the past, I already added the export to Markdown but the export to Excel and other formats was only in plans.

But today I published an update and now SteemSQL Wrapper has the support of the export to Excel, CSV, and JSON. It is helpful to users who want to create a complex analysis but do not want or cannot connect to SteemSQL from their spreadsheet app. Also, it is helpful in all cases when you want to create graphs from the Steemit data because right now SteemSQL Wrapper does not have any features for this.

After a click, a file will automatically start downloading. The Markdown export works the same as before.

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