Merge pull request redis#356 from domodwyer/v4

Add Cmd constructors for testing/mock purposes.

Merge pull request redis#355 from go-redis/fix/geo-pos-rename

Fix/geo pos rename

Merge pull request redis#352 from jrmarkle/process_wrapper

add WrapProcess to allow users to alter command processing

Merge pull request redis#350 from go-redis/fix/ring-heartbeat-frequency

ring: reduce HeartbeatFrequency.

Merge pull request redis#347 from flisky/master

fix iterator for hscan/sscan/zscan

Merge pull request redis#344 from go-redis/fix/rename-commander

Rename Commander to Cmdable to match internal name.

Merge pull request redis#340 from go-redis/fix/setbit

Fix Del command case.

Fix Del command case.

Merge pull request redis#336 from go-redis/fix/read-line-strict

Make readLine more strict.

Make readLine more strict.