Feature: Extend 'watched achievements' feature to arbitrary tasks

[bever1337]

Gwapo users should be able to use a feature similar to 'watch achievement' for arbitrary tasks and items. For example, a user may 'watch' a legendary item. Once the item is 'watched', then it appears in the user's task manager. Later, 'watched' tasks can be used to recommend gathering nodes, daily achievements, and other micro-tasks.