add more properties (#12)

Also moved *girth* from `Integer` to `Real`, as it is positive infinity for acyclic undirected graphs.

Author: nsajko

src/GraphProperties.jl

@@ -48,6 +48,11 @@ let
         (:FractionalChromaticNumber, "The *fractional chromatic number* of an undirected graph."),
         (:FractionalMatchingNumber, "The *fractional matching number* of an undirected graph."),
         (:Strength, "The *strength* of an undirected graph."),
+        (:AssortativityCoefficient, "The *assortativity coefficient* of an undirected graph."),
+        (:GlobalClusteringCoefficient, "The *global clustering coefficient* of an undirected graph."),
+        (:CheegerConstant, "The *Cheeger constant* of an undirected graph. Also known as the *Cheeger number* or as the *isoperimetric number*."),
+        (:Circumference, "The *circumference* of an undirected graph."),
+        (:Girth, "The *girth* of an undirected graph."),
     ]
     properties_integer = Tuple{Symbol, String}[
         (:NumberOfVertices, "The *number of vertices* of a graph."),
@@ -60,7 +65,9 @@ let
         (:MaximumIndegree, "The *maximum indegree* among the indegrees of the vertices of a directed graph."),
         (:MinimumOutdegree, "The *minimum outdegree* among the outdegrees of the vertices of a directed graph."),
         (:MaximumOutdegree, "The *maximum outdegree* among the outdegrees of the vertices of a directed graph."),
-        (:Girth, "The *girth* of a undirected graph: the length of its shortest cycle."),
+        (:Radius, "The *radius* of a connected undirected graph."),
+        (:Diameter, "The *diameter* of a connected undirected graph."),
+        (:Triameter, "The *triameter* of a connected undirected graph."),
         (:VertexConnectivity, "The *vertex-connectivity* of an undirected graph. Also known as the *connectivity*."),
         (:EdgeConnectivity, "The *edge-connectivity* of an undirected graph."),
         (:CliqueNumber, "The *clique number* of an undirected graph."),
@@ -79,6 +86,8 @@ let
         (:HadwigerNumber, "The *Hadwiger number* of an undirected graph. Also known as the *contraction clique number* or as the *homomorphism degree*."),
         (:TwinWidth, "The *twin-width* of an undirected graph."),
         (:CliqueWidth, "The *clique-width* of an undirected graph."),
+        (:TreeDepth, "The *tree-depth* of a connected undirected graph."),
+        (:CycleRank, "The *cycle rank* of a directed graph."),
         (:Treewidth, "The *treewidth* of an undirected graph."),
         (:Pathwidth, "The *pathwidth* of an undirected graph. Also known as the *interval thickness* or as the *vertex separation number* or as the *node searching number*."),
         (:Boxicity, "The *boxicity* of an undirected graph."),