Implement per-column table styling

[RacingTadpole]

Fixes #1097.

Columns can be specified by either their name in the csv file, or their position (0 for the first column, etc). I've added name and type to the list of tableStyle parameters that apply in tableStyle.columns.

An example is the final catalog item at http://localhost:3001/#build/terriajs/test/init/test-tablestyle.json .

One implementation decision I've made, which we can discuss, is: if you supply a new name for a column, but not a type, its type is guessed based on the new name, not its old name.

Unsupported in this PR:

• Setting columns.x.type to region
• columns.x.regionType
• Columns cannot be specified by regex.

[AlexGilleran]

Should this have the values of the potential options like in other constructors that take options hashes?

[RacingTadpole]

Very true. I just copied it over from TableStyle, which didn't have it either. But I'll add it.

[AlexGilleran]

So cool 🌈 .

As discussed on slack though:

 "columns": {
               "Value": {
                 "name": "Postal code"
               },
}

results in:

Probably should say "Postal code" not "Value" :).

[RacingTadpole]

@AlexGilleran: I've added your suggestions now. I've also built on this quite a bit in #1307, and I might have cleaned up some things there that really should be here... sorry...