Experimental natural language search in grid

[Massimo]

Given 

db.define_table('thing', Field('name'))

and

@action("grid")

@action.uses(auth, "generic.html")

def _():

grid = Grid(db.thing)

return locals()

The grid now provides, by default, a natural language search box

You search like:

name is not null

name is Cat

name is "Cat"

name belongs Cat,Dog,"Funny Hippo" or (not name contains "x" and id is greater than 3)

quotes are optional. You can use (...) to group. You can use normal == != < > <= >= operators.

I could use some help testing before I publish this.

[Massimo]

Here is a new experimental grid using this https://github.com/web2py/py4web/pull/974