Add support for markdown tables

Closes #85

* Split Border into BoxBorder and TableBorder
* Change how different table parts are composed
* Add markdown table border

docs/input/appendix/borders.md

@@ -4,16 +4,30 @@ Order: 2
 
 There is different built-in borders you can use for tables and panels.
 
-# Built-in borders
+# Table borders
 
-<img src="../assets/images/borders.png" style="max-width: 100%;">
+<img src="../assets/images/borders/table.png" style="max-width: 100%;">
 
-# Usage
+## Example
 
-To create a table and set it's border to `SimpleHeavy` as seen in the 
-image above:
+To set a table border to `SimpleHeavy`:
 
 ```csharp
 var table = new Table();
-table.Border = Border.SimpleHeavy;
+table.Border = TableBorder.SimpleHeavy;
+```
+
+---
+
+# Panel borders
+
+<img src="../assets/images/borders/panel.png" style="max-width: 100%;">
+
+## Example
+
+To set a panel border to `Rounded`:
+
+```csharp
+var panel = new Panel("Hello World");
+panel.Border = BoxBorder.Rounded;
 ```