Previously, images were deleted only from comments deleted
before EditDuration expiration. After this change, any deletion
of the comment deletes images if they are not used elsewhere
in comments under the same page.
Fixes the following conversion problem for BlockedUser:
```
panic: interface conversion: interface {} is map[string]interface {},
not store.BlockedUser [recovered]
```
Resolves#1475.
@paskal
* sort imports, add missing copyright
* regenerate engine mock
* make all image.Store interface functions public
* go mod tidy
* make image.Store.Load return []byte instead of io.ReadCloser
* separate memory_store example RPC server to multiple files by handlers groups
* explicitly ignore error from test connection close
* add client with timeout to places which used default http client
* move random port creation and waiting for server in separate function for reuse
* improve TestServer tests robustness
* move all server waiting code in tests to separate functions
* change chooseRandomUnusedPort to try to listen to port before return
* fix waitForHTTPSServerStart
* implement (strings) user details storage
* add rpc user details implementation
* return error from getUserDetail, rewrite tests to table tests
* make UserDetails store UserDetailEntry instead of strings
* update comment about user_details
* fix confusing return
* add user details support for memory store
* add engine.UserDetailEntry to service.UserMetaData
* add ListDetails support to memory storage
* add user details support to native migrator, ListDetails func to storage
* go mod tidy for memory storage
* increase memory storage test coverage, fix tests naming
* add ListDetails tests to memory storage
* add engine.ListDetails and service.[Set]Metas tests
* change Fprintf to Fprint (triggered by explicitly ignoring error)
* remove Delete from engine.UserDetail, implement list via same method
* adjust service.Metas to new engine.UserDetails signature
* introduce engine.UserDetail("all") consonant
* fix Meta user detail retrieval
* extend store implementations Delete method with UserDetail deletion
* make UserDetail test answer order-independent
* fix flaky test check in TestMemData_FlagListBlocked
* delete user details alongside with comments on deleteme request
* add tests to UserDetail store.Delete implementations
* clarify engine module user details consonants names
* update comments to reflect current state of code
* check for value absence instead of it's length
* revert unneeded code change
* add extensive commentary on UserDetail return type
* remove unused check condition
* clarify UserDetail tests to be truly stateless
* add clarifying comment for pre-table test
* make tests more resilient
* adjust drone for v1.x and dev-box, remove travis support
* add backend build step on branch for drone
* fix from email
* change notif email
* less demanding test wait
* add settings section to drone plugins
* adjust branch build
* convert all drone ci docker confs
* rename drone targets
Dmitry VerkhoturovandUmputun
