add do-block way to create/open a database, given a schema

src/InMemoryLoggedDB.jl

@@ -10,6 +10,7 @@ using MsgPack
 
 include("actions.jl")
 include("structure.jl")
+include("db_init.jl")
 
 function Base.push!(stream::IOStream, object::T) where T
     write(stream, Action(create, object))

src/db_init.jl

@@ -0,0 +1,14 @@
+"DataBase(path) do db:DataBase
+end
+
+Load a database, or create it from a schema"
+function DataBase(f, path::String)
+    db = if isdir(path)
+        DataBase(path, verbose = true);
+    else
+        let db = DataBase(path, verbose = true);
+            f(db)
+            db
+        end
+    end
+end