Subsocial v0.4.0

Closed issues

• Extract pallets: space-history, posts-history, profile-history #31
• Clean up Cargo.toml-s after split-refactoring. There could be some unused dependencies #28
• Update types.json after split of social pallet completed #25
• Do full comparison of permissions in update_role() #24
• Add parent_id to Space struct #23
• Rename in SpacePermission enum: ***Any***s -> ***Any*** #17
• Refactor ipfs_hash to Content enum #16
• Move edit_history from structs to separate pallets #12
• Create Roles pallet #6
• Do not lowercase a blog handle #4

Merged pull requests

• Betanet (includes creation of 1k spaces) #50
• Add session keys pallet #49
• Implement permissions override feature for Spaces #47
• Refactor Profile's username to a handle similar to Space's one #46
• Slightly refactor Post pallet #45
• Update Substrate version to v2.0.0-rc4 #43
• Extract edit history to new pallets #42
• Add parent_id to Space struct #37
• Refactor IPFS hash to Content #36
• Move tests from before the monolith pallet was split #29
• Update types.json after split of social pallet #26
• Split social pallet into smaller pallets #19
• Split social's functions into more files #18
• Loose coupling of pallets: Roles + Social #10
• Add Subsocial pallets: social, permissions, roles, etc #9