Add GraphProperties and property caching

docs/src/lib/internals/properties.md

@@ -0,0 +1,22 @@
+# Properties
+
+## Type
+```@autodocs
+Modules = [MetagraphOptimization]
+Pages = ["properties/type.jl"]
+Order   = [:type]
+```
+
+## Create
+```@autodocs
+Modules = [MetagraphOptimization]
+Pages = ["task/create.jl"]
+Order   = [:function]
+```
+
+## Utility
+```@autodocs
+Modules = [MetagraphOptimization]
+Pages = ["properties/utility.jl"]
+Order   = [:function]
+```