Simple fixes

Just fixing a couple of small issues.

Simple item removal

This release introduces a simple removal of items. It is limited to attempting a quiz. Please read the change log and readme for more details.

Leaderboards

This adds leaderboards that can be displayed in the block. It also includes some additional web services in preparation of a new plugin "tiny stash". Tiny stash is a TinyMCE plugin that allows you to create, configure, and add item and trades from the editor.

User group trading restriction

This release adds a new option that allows users to restrict trading between users to the groups that they belong to.
See the CHANGELOG.md file for further information of other changes.

Version 2 bug fixes and minor improvements

After the huge amount of code included in the 2.0 release there were some bugs that popped up. This fixes the ones reported, and also includes some improvements to labels for trading, and a web service for use in other projects.

User trading

We have introduced basic trading between students!
Students can go to the trade center and search for students, or items to begin a trade. Once created a notification will appear in the stash block for the student. They can then go to the 'Offers' page to view, accept, or decline the offer.

Small bug fixes

This release is very small. It fixes up two bugs:

1. The deprecation of a function for fetching user fields. We are now using core_user\fields::get_picture_fields
2. Trades not showing properly due to the stdClass not being defined.

I have been playing around with other enhancements to block_stash, but I'll only post details for them when they are finished.
Thank you for your support and I hope that you continue to enjoy stash with Moodle.

v1.3.3: single_item_reset: Indiviual items for a user can be updated.

This is all done through the report page. You can add items and
change the quantities.