Implement Renewing Functionality

[kittsville]

Implement ability to renew items on loan so that they can continue to remain with a member, avoiding need to 'return' item to then loan it straight after. This distinction would avoid a single extended loan being kept track of as two or more seperare loans, and would avoid the item being incorrectly noted as being returned and re-loaned.

Renewing functionality could be achieved by updating an item's due date, while adding loan meta to distinguish between regular loans and to keep track of the number of times an item has been loaned.

Further functionality could be implemented to limit the number of times an item can be loaned.

[kittsville]

Implemented by dd23ecd

Will close once details of each renewal are visible on the Dash

[kittsville]

Currently each table row displays (as one would expect) the updated due date caused by the renewing. This means no part of the page displays the original due date of the loan.

[kittsville]

As the purpose of the original issue has been fulfilled, this issue will be closed. The new issue created in the process of implementing this issue will be continued with issue #30