Resolve "TransactionDocument: replace Vec fields by SmallVec"

Closes #197

lib/dubp/user-docs/src/documents/mod.rs

@@ -40,10 +40,10 @@ pub enum UserDocumentDUBP {
     Transaction(Box<TransactionDocument>),
 
     /// Identity document.
-    Identity(IdentityDocument),
+    Identity(Box<IdentityDocument>),
 
     /// Membership document.
-    Membership(MembershipDocument),
+    Membership(Box<MembershipDocument>),
 
     /// Certification document.
     Certification(Box<CertificationDocument>),
@@ -135,11 +135,11 @@ impl UserDocumentDUBP {
         let doc_type_v10_pair = unwrap!(pair.into_inner().next()); // get and unwrap the `{DOC_TYPE}_v10` rule; never fails
 
         match doc_type_v10_pair.as_rule() {
-            Rule::idty_v10 => Ok(UserDocumentDUBP::Identity(IdentityDocument::V10(
+            Rule::idty_v10 => Ok(UserDocumentDUBP::Identity(Box::new(IdentityDocument::V10(
                 IdentityDocumentV10::from_pest_pair(doc_type_v10_pair)?,
-            ))),
-            Rule::membership_v10 => Ok(UserDocumentDUBP::Membership(MembershipDocument::V10(
-                MembershipDocumentV10::from_pest_pair(doc_type_v10_pair)?,
+            )))),
+            Rule::membership_v10 => Ok(UserDocumentDUBP::Membership(Box::new(
+                MembershipDocument::V10(MembershipDocumentV10::from_pest_pair(doc_type_v10_pair)?),
             ))),
             Rule::cert_v10 => Ok(UserDocumentDUBP::Certification(Box::new(
                 CertificationDocument::V10(CertificationDocumentV10::from_pest_pair(