get_item_list does not [item qty=0]

- By using `if not d.qty:` it totally limits the chance of creating an empty Delivery Note 
- Should be changed to `if d.qty is None` 

Use case for empty DN: 
- Open a Delivery Note and tight to a specific Sales Order first without knowing the real qty at this point.
- Using barcode scanner to receive Sales Order to this DN (multiple times).
Merge pull request #2140 from nathando/patch-1

get_item_list does not [item qty=0]
Merge pull request #2162 from nabinhait/hotfix

Get items in PO from material requests based on supplier
[fix] Clear website cache for Item Group on saving Item
[minor] Cheque Printing Format
Merge pull request #2165 from anandpdoshi/anand-september-9

Fix in web clear cache for Item, cheque printing format
change version in hooks.py
bumped to version 4.3.0
Merge branch 'develop'
Set allow_on_submit for 'page_break', 'letter_head', 'select_print_heading', 'print_heading'. Fixes frappe/erpnext#1810
Merge pull request #2167 from anandpdoshi/anand-september-9

Set allow_on_submit for 'page_break', 'letter_head', 'select_print_heading', 'print_heading'. Fixes frappe/erpnext#1810
Opening entry should not be considered in bank reconciliation statement