Merge pull request #4 from KwaMoja/develop

Develop
Ensure variables are set before you use them, and remove redundant code
Fix installer error
David Lynn: added url to suppliers
Improvements to layout
Merge pull request #262 from timschofield/develop

Develop
Change default rounding to two decimal places from zero
New script to create purchase orders by preferred supplier
Bring the new script into line with coding guidelines, and fix minor bugs
New script to upload sales price lists
Change the name of the new script and bring into line with coding guidelines
Database updates for the new script
Merge pull request #263 from timschofield/develop

Develop