Gorse v0.5.0-alpha.8

Warning This is a pre-release version of the Gorse recommender system. It means:

1. Don't use the pre-release version in production unless you can afford the risks.
2. APIs, configurations, and data storage might be changed between pre-release versions.
3. Clear local caches and cache databases after the upgrade.

Performance

• Fix CPU contention of gorse-in-one (#1092).
• Cache items for workers on demand (#1093).
• Skip cold-start users in offline recommendation (#1095).

Fix

• Add non-persoanlized recommendation digest (#1086).
• Return zero values instead of errors when cache values don't exist (#1088).
• Fix import feedback with value (#1090).

BREAK CHANGES

• Implement new multi-way ranker (#1077).
• Convert euclidean distance to similarity (#1091).
• Load playground data from binary dump (#1100).