Show nulls

[RobinDeeCee]

Issue

#3412

Details

• adding a vlag to allow to show null values
• checking if this vlag is on, if yes show a X

[netil]

IMO isn't really necessary to add new option here. when the value is null, just showing a "blank" will be okay.

[netil]

@RobinDeeCee, thanks for the contribution!
I'll review and update necessary codes to merge.

I think null should also be handled, but not in a separate option for that.

[netil]

updated option to specify how null data will be shown.

  plugins: [
    new bb.plugin.tableview({
         ...
	nullString: "N/A"  // for null value, 'N/A' string will be shown.
    })
  ]