Add profile support

Closes #231

src/Spectre.Console/Internal/Text/Markup/MarkupParser.cs

@@ -2,7 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
-namespace Spectre.Console.Internal
+namespace Spectre.Console
 {
     internal static class MarkupParser
     {

src/Spectre.Console/Internal/Text/Markup/MarkupToken.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace Spectre.Console.Internal
+namespace Spectre.Console
 {
     internal sealed class MarkupToken
     {

src/Spectre.Console/Internal/Text/Markup/MarkupTokenKind.cs

@@ -1,4 +1,4 @@
-namespace Spectre.Console.Internal
+namespace Spectre.Console
 {
     internal enum MarkupTokenKind
     {

src/Spectre.Console/Internal/Text/Markup/MarkupTokenizer.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Text;
 
-namespace Spectre.Console.Internal
+namespace Spectre.Console
 {
     internal sealed class MarkupTokenizer : IDisposable
     {