Added Workflow State token provider.

This token provider enables tokenized fields to access WorkflowContext state values.
Example: {Workflow.State:MyData.MyProperty.SubProperty}

src/Orchard.Web/Modules/Orchard.Workflows/Orchard.Workflows.csproj

@@ -176,6 +176,7 @@
     <Compile Include="Services\IWorkflowManager.cs" />
     <Compile Include="Services\WorkflowManager.cs" />
     <Compile Include="Tokens\SignalTokens.cs" />
+    <Compile Include="Tokens\StateTokens.cs" />
     <Compile Include="ViewModels\AdminEditViewModel.cs" />
     <Compile Include="ViewModels\AdminIndexViewModel.cs" />
     <Compile Include="ViewModels\WorkflowDefinitionViewModel.cs" />

src/Orchard.Web/Modules/Orchard.Workflows/Tokens/StateTokens.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Linq;
+using Orchard.Tokens;
+using Orchard.Workflows.Models;
+
+namespace Orchard.Workflows.Tokens {
+    public class StateTokens : Component, ITokenProvider {
+
+        public void Describe(DescribeContext context) {
+            context.For("Workflow", T("Workflow"), T("Workflow tokens."))
+                .Token("State:*", T("State:<workflowcontext path>"), T("The workflow context state to access. Workflow.State:MyData.MyProperty.SubProperty"))
+            ;
+        }
+
+        public void Evaluate(EvaluateContext context) {
+            context.For<WorkflowContext>("Workflow")
+                .Token(token => token.StartsWith("State:", StringComparison.OrdinalIgnoreCase) ? token.Substring("State:".Length) : null, ParseState);
+        }
+
+        /// <summary>
+        /// Resolves the specified expression into an object stored in WorkflowContext.
+        /// </summary>
+        /// <param name="expression">The expression resolving to the state stored in WorkflowContext. E.g. "MyData.MyProperty.MySubProperty"</param>
+        private object ParseState(string expression, WorkflowContext workflowContext) {
+            var path = expression.Split(new[] {'.'}, StringSplitOptions.RemoveEmptyEntries);
+            var first = path.First();
+            var obj = (dynamic)workflowContext.GetState(first);
+
+            if (path.Length > 1) {
+                foreach (var property in path.Skip(1)) {
+                    obj = obj[property];
+                }
+            }
+
+            return obj;
+        }
+    }
+}