Data Grid Widget

Feel free to comment additional suggestions.

## Background
Although the table API is powerful, it is not the most friendly API for users wanting to quickly display data and requires a lot of manual setup. A higher level API written on top of the table API is desired. Something similar to the 0.6 simple table API but more powerful.

## Required Functionality
* Performant - easily display 100k's of rows
* Easy
* Column level control item types
* Per-column settings
* Sizing policies
* Row/column appending
* Row/column insertion
* Sorting
* Row/column deletion
* Filtering
* Selections
* Reordering
* Other settings

## Methods
This will be object oriented and thus will be operated on through various methods. Below are the current public non-obvious methods:
* `insert_column(...)` & `insert_row(...)`
* `append_row(...)` & `append_column(...)`
* `delete_row(...)` & `delete_column(...)`
* `get_cell_value(...)` & `set_cell_value(...)`
* `hide_column(...)` & `show_column(...)`
* `hide_row(...)` & `show_row(...)`
* `get_column(...)` & `set_column(...)`
* `get_row(...)` & `set_row(...)`
* `get_selections(...)` & `set_selections(...)`
* `highlight_row(...)` & `highlight_column(...)` & `highlight_cell(...)` & undoing these