Checks types.

var is = require('isita');
is.array([])
is.date(new Date)
is.null(null)
is.color(0xFFFFFF)
is.function(is.function)

etc.

Supported:

- nan
- array
- date
- regexp
- number
- string
- boolean
- function
- undefined
- null
- integer
- positive
- negative
- finite
- natural
- color