[#388] *: Remove nil check from setters

I knew one day `sed` would save me an hour of manual work:
```
sed -i -n -e '
s/) Set/) Set/
p
t setter
b end
:setter
    n
    s/nil/nil/
    t hasif
    p
    b end
    :hasif
        n
        :loop
        p
        n
        s/}/}/
        t end
        b loop
        :end
' $@
goimports -w $@
```

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

acl/grpc/types.go

@@ -6,149 +6,107 @@ import (
 
 // SetVersion sets version of EACL rules in table.
 func (m *EACLTable) SetVersion(v *refs.Version) {
-	if m != nil {
-		m.Version = v
-	}
+	m.Version = v
 }
 
 // SetContainerId sets container identifier of the eACL table.
 func (m *EACLTable) SetContainerId(v *refs.ContainerID) {
-	if m != nil {
-		m.ContainerId = v
-	}
+	m.ContainerId = v
 }
 
 // SetRecords sets record list of the eACL table.
 func (m *EACLTable) SetRecords(v []*EACLRecord) {
-	if m != nil {
-		m.Records = v
-	}
+	m.Records = v
 }
 
 // SetOperation sets operation of the eACL record.
 func (m *EACLRecord) SetOperation(v Operation) {
-	if m != nil {
-		m.Operation = v
-	}
+	m.Operation = v
 }
 
 // SetAction sets action of the eACL record.
 func (m *EACLRecord) SetAction(v Action) {
-	if m != nil {
-		m.Action = v
-	}
+	m.Action = v
 }
 
 // SetFilters sets filter list of the eACL record.
 func (m *EACLRecord) SetFilters(v []*EACLRecord_Filter) {
-	if m != nil {
-		m.Filters = v
-	}
+	m.Filters = v
 }
 
 // SetTargets sets target list of the eACL record.
 func (m *EACLRecord) SetTargets(v []*EACLRecord_Target) {
-	if m != nil {
-		m.Targets = v
-	}
+	m.Targets = v
 }
 
 // SetHeader sets header type of the eACL filter.
 func (m *EACLRecord_Filter) SetHeader(v HeaderType) {
-	if m != nil {
-		m.HeaderType = v
-	}
+	m.HeaderType = v
 }
 
 // SetMatchType sets match type of the eACL filter.
 func (m *EACLRecord_Filter) SetMatchType(v MatchType) {
-	if m != nil {
-		m.MatchType = v
-	}
+	m.MatchType = v
 }
 
 // SetKey sets key of the eACL filter.
 func (m *EACLRecord_Filter) SetKey(v string) {
-	if m != nil {
-		m.Key = v
-	}
+	m.Key = v
 }
 
 // SetValue sets value of the eACL filter.
 func (m *EACLRecord_Filter) SetValue(v string) {
-	if m != nil {
-		m.Value = v
-	}
+	m.Value = v
 }
 
 // SetRole sets target group of the eACL target.
 func (m *EACLRecord_Target) SetRole(v Role) {
-	if m != nil {
-		m.Role = v
-	}
+	m.Role = v
 }
 
 // SetKeys of the eACL target.
 func (m *EACLRecord_Target) SetKeys(v [][]byte) {
-	if m != nil {
-		m.Keys = v
-	}
+	m.Keys = v
 }
 
 // SetEaclTable sets eACL table of the bearer token.
 func (m *BearerToken_Body) SetEaclTable(v *EACLTable) {
-	if m != nil {
-		m.EaclTable = v
-	}
+	m.EaclTable = v
 }
 
 // SetOwnerId sets identifier of the bearer token owner.
 func (m *BearerToken_Body) SetOwnerId(v *refs.OwnerID) {
-	if m != nil {
-		m.OwnerId = v
-	}
+	m.OwnerId = v
 }
 
 // SetLifetime sets lifetime of the bearer token.
 func (m *BearerToken_Body) SetLifetime(v *BearerToken_Body_TokenLifetime) {
-	if m != nil {
-		m.Lifetime = v
-	}
+	m.Lifetime = v
 }
 
 // SetBody sets bearer token body.
 func (m *BearerToken) SetBody(v *BearerToken_Body) {
-	if m != nil {
-		m.Body = v
-	}
+	m.Body = v
 }
 
 // SetSignature sets bearer token signature.
 func (m *BearerToken) SetSignature(v *refs.Signature) {
-	if m != nil {
-		m.Signature = v
-	}
+	m.Signature = v
 }
 
 // SetExp sets epoch number of the token expiration.
 func (m *BearerToken_Body_TokenLifetime) SetExp(v uint64) {
-	if m != nil {
-		m.Exp = v
-	}
+	m.Exp = v
 }
 
 // SetNbf sets starting epoch number of the token.
 func (m *BearerToken_Body_TokenLifetime) SetNbf(v uint64) {
-	if m != nil {
-		m.Nbf = v
-	}
+	m.Nbf = v
 }
 
 // SetIat sets the number of the epoch in which the token was issued.
 func (m *BearerToken_Body_TokenLifetime) SetIat(v uint64) {
-	if m != nil {
-		m.Iat = v
-	}
+	m.Iat = v
 }
 
 // FromString parses Action from a string representation,