Fix inverted arguments for a collision callback

The start and stop callbacks on this line seem to be backwards.
Fixed a couple of errors in the methods definition
Added my own IDE filed in the .gitignore file
Added a destroy method on the Gridster class
Bound leftover callbacks are one of the main causes of memory leaks, let's remove them inside the destroy method
Built new version
Fixed a minor issue when trying to destroy a non existing drag_api
Merge pull request #76 from pushmatrix/master

Fix inverted arguments for a collision callback
Merge pull request #125 from brokenseal/master

Possible solution to memory leak #124
Fix for not removing stylesheets on destroy
Add max_cols setting

Right now the number of columns is calculated by dividing the available
space by the necessary space. I want to have an option to limit the
number of calculated columns, without changing the width of the div my
grid lives in.

In order to limit the number of calculated columns max_cols is set to a
number. To have 'unlimited' columns set the value of max_cols to -1 (as
ids done in the default settings). This provides the arbitrary useful
functionality to set the max number of columns to 0. Any sideeffect
caused by this are mitigated by checking that the max_cols is larger
than the min_cols setting.
Merge pull request #154 from tuvokki/master

Add setting for maximum number of columns
Merge pull request #152 from rfink/master

Fix for issue #46
Updated to latest version of Grunt
Updated Readme added PSA
Fixed is_empty method
resize_widget function with callback parameter

Is it possible to add a callback to the resize_widget function, that is
called when the resizing of a widget is finished? This may help to
update the widget content properly.
Merge pull request #169 from tuvokki/master

Fix for Issue #158
Add Gruntfile
Updated Readme
Merge pull request #165 from matiangul/master

Fix is_empty method