Alpha version of label indexes.

Squashed messages from 9 commits:

9.
Properties now uses PropertyFamily and contained classes.
Fetching,seting,clearing properties can be done with PropertyFamilyKey or PropertyTypeKey.
Hierarchy of newly added clases is:
Vertices -n-> PropertyFamily {name: String} <-1-n-> PropertyType {type: Property::Flags}
Edges -n-> PropertyFamily {name: String} <-1-n-> PropertyType {type: Property::Flags}

PropertyFamilyKey -> PropertyType
PropertyTypeKey -> PropertyType

PropertyType t0,t1;
let t0!=t1 be true
let t0.family==t1.family be true

then next is true
PropertyTypeKey{&t0}!=PropertyTypeKey{&t1}
PropertyFamilyKey{&t0}==PropertyFamilyKey{&t1}
PropertyFamilyKey{&t0}==PropertyTypeKey{&t1}
PropertyTypeKey{&t0}==PropertyFamilyKey{&t1}

8.
Intermedate commit.
Noticed that integration queries throw SEGFAULT.

7.
Defined interface for indexes.
Fixed three memory leaks.
Fixed integration_queries test which now passes.

6.
Commit which return Xorshift128plus to valid shape.

5.
Tmp commit.

4.
Label Index is compiling.

3.
tmp

2.
Vertex::Accessor now updates Label index.

1.
Applied changes for code review.

include/utils/border.hpp

@@ -0,0 +1,51 @@
+#pragma once
+
+#include "utils/option.hpp"
+
+// Defines Including as [ and Excluding < for ranges.
+enum BorderType
+{
+    Including = 0,
+    Excluding = 1,
+};
+
+template <class T>
+class Border
+{
+
+public:
+    Border() : key(Option<T>()), type(Including) {}
+    Border(T Tey, BorderType type) : key(Option<T>(std::move(key))), type(type)
+    {
+    }
+
+    // Border(Border &other) = default;
+    Border(Border &other) = default;
+    Border(Border &&other) = default;
+
+    Border &operator=(Border &&other) = default;
+    Border &operator=(Border &other) = default;
+
+    // true if no border or this>key or this>=key depends on border type.
+    bool operator>(const T &other) const
+    {
+        return !key.is_present() || key.get() > other ||
+               (type == Including && key.get() == other);
+    }
+
+    // true if no border or this<key or this<=key depends on border type.
+    bool operator<(const T &other) const
+    {
+        return !key.is_present() || key.get() < other ||
+               (type == Including && key.get() == other);
+    }
+
+    Option<T> key;
+    const BorderType type;
+};
+
+template <class T>
+auto make_inf_border()
+{
+    return Border<T>();
+}