Rucksacks.

Current release 1.17.1-0.2.0.8

• Update build.gradle - Mawathilde
• Colored Rucksacks - Mawathilde

1.17.1-0.1.1

• Optimize methods (Rucksack container) - Mawathilde
• fix fields names & add basic javadoc - Mawathilde
• remove unused method & rename ItemInit -> ItemConstants - Mawathilde
• update mod structure & downgrade to forge version 37.0.50 - Mawathilde
• Update README.md - Mathilde
• Add recipe advancement for leather rucksack - Mawathilde
• fix version range - Mawathilde
• add leather rucksack item - Mawathilde