Custom type + custom cell renderer + custom header cell renderer

[vitolpoc]

Add ability to define custom types, custom cell renderer and custom header cell renderer for default and custom types: “string”, “numeric”, “date”, “currency” etc … without having to specify it for each column definition (i.e. as a default configuration) or as a specific column configuration.

[roblotter]

We're almost done implementing column types - need to document it thoroughly and it's ready to ship