Add table UI widget

[arnobaer]

Add a simple to use table widget.

table = comet.Table(header=["Key", "Value"])
table.append(["spam", 1000])
table.append(["ham", 2000])
table.append(["eggs", 3000])
for row in table:
    row[0].checked = True # set check state
    row[0].color = "blue"