iTrack Pro v1.4

Merge pull request #211 from junhaotan/master

Remove unused code

v1.3.1

Updated UG and error messages for commands. Fixed some bugs

v1.3

Merge pull request #135 from YingxuH/update-userguide

Update userguide

v1.2.1

Merge pull request #105 from junhaotan/master

Add notification popup window when product quantity drops below threshold

v1.2

Merge pull request #90 from YingxuH/link-transactions

Link transactions with product and customer

v1.1

Merge pull request #27 from YingxuH/update-userguide

Update userguide