Breaking(expandable): add ngdoc, standardise option names and format

[PaulL1]

In particular changes are:

• all options moved from gridOptions.expandable.xxx to gridOptions.expandableXxxx
• rowExpandableTemplate changed to expandableRowTemplate
• defaults added for row height
• error check added for rowExpandableTemplate, module is disabled with an error
  message if not present
• overall enableExpandable option provided

[PaulL1]

@novice3030 @jpuri : note this pull request, it is breaking change on the expandable module, which will impact you.

[wattsbn]

I don't think you have added the logError function yet have you?

[PaulL1]

Bother. Yes, you're right. The PR is in, but the code isn't actually merged. Hmmm. I guess it'll throw an error until it's there, which is pretty much what it did before I added that extra code.

[jpuri]

Hey Paul,
Thanks for this good work and taking the left overs from expandable functionality. I was also thinking the expandable functionality needs some work. Some work can also be done to increase its test coverage, I will spend some time on that might be next month.

[PaulL1]

Agree that it could use some work. I think the biggest outstanding is that it is really impacting scroll performance. I notice that it uses a lot of ng-if type logic, and I wonder whether that can be replaced by event handlers and $compile/append type logic, as the guys have used in other areas.

I'd like to write some documentation on that, refer #1819, which might be done by then and provide some hints and tips on how this could be done.

[jpuri]

Hi Paul,
One of the reasons for bad scroll performance is the 2 containers logic, I am not sure what it is but you will see similar performance impact with row selection feature also. In addition the scroll performs bad even when grid all All Collapsed.