Add category selection settings to popup and other small fixes:
- Removed inline script from popup due to being against chrome's policy
- Fixed outdated comments
- Fixed popup values not being stored correctly all the time
- Now storing the API items categories together with the rest of the data
- Updated how items categories are fetched from the DOM (different element attribute that matches with the API data)
- Bazaar script now filters out items not on the predefined categories.
- Updated popup with new table that allows to select in which categories the profit elements should show up
- Bazaar and Market now filter out items based on desired settings (popup selection)
- Remove previously hardcoded categories
- Other small fixes like early returns and extra undefined checks
- Bumped version to 0.1.3

- Fixed the price update script on the listing page
- Cleaned up old parts of the code base