Hide and show columns, allow for zero to 3 columns, query param for numColumns

[Gaurav0]

Relevant to #65, #100, #122

[HeroicEric]

Might be nice to refactor this to use a computed property rather than an observer

[Gaurav0]

This PR is complete. Please review.

[Gaurav0]

@stefanpenner @joostdevries @rwjblue Updated. Pretty please review.

[stefanpenner]

I'm curious, it seems like rather then making this controller have array like qualities. Having the columns represented off-object would be clean. Something like:

controller.columns === [
  col1,
  col2,
  col3
]

columns: computed('dataColumnsNeed', function() {
  return ensureColums(this.get('dataColumnsNeed'))
});

the return columns object itself doesn't need to be an array, but may prove to be nice if it ways.

This would also make it easy to support N columns, if we are so inclined, but also begins to move to a pull based system over the imperative model.

some relevant code this would tidy up nicely:

• https://github.com/ember-cli/ember-twiddle/pull/141/files#r37147263
• https://github.com/ember-cli/ember-twiddle/pull/141/files#r37147269
• also the set related code

[Gaurav0]

@stefanpenner Updated. Could you please review again?

[stefanpenner]

this CP at first glance appears to indicate, it will provide the last column. But after reading the implementation it seems to actually return true/false. Maybe it should be isLastColumn ?

[Gaurav0]

Ok, done.

[stefanpenner]

should likely not put a complex object on the prototype, especially if it is meant to hold instance state.

Likley either set this in the constructor, or make it a cp.

[Gaurav0]

Setting in constructor.

[Gaurav0]

@stefanpenner Are there any further issues or may I merge this?