Basalt 1.7 Update

- New Objects (Flexbox, Graph, Treeview)
- Pluginsystem to add/remove functionality
- Reworked the entire Object system, instead of one big Object Class we have multiple classes: Object, VisualObject, ChangeableObject
- Instead of one big Frame Class we have multiple Frame Classes: BaseFrame, Frame, MovableFrame, ScrollableFrame, MonitorFrame, Flexbox
- Removed the Animation Object, and added a animation plugin instead
- Removed the Graphic Object and merged it's functionality with the image object
- Updated currently existing objects

docs/docs1_6/objects/Checkbox.md

@@ -0,0 +1,33 @@
+With checkbox objects the user can set a bool to true or false
+
+Remember checkbox also inherits from [Object](objects/Object.md)
+
+A checkbox does not have any custom methods. All required methods are provided by the base [object](objects/Object.md) class.
+
+# Example
+This is how you would create a event which gets fired as soon as the value gets changed:
+```lua
+local mainFrame = basalt.createFrame()
+local aCheckbox = mainFrame:addCheckbox()
+
+local function checkboxChange(self)
+   local checked = self:getValue()
+   basalt.debug("The value got changed into ", checked)
+end
+aCheckbox:onChange(checkboxChange)
+```
+
+also possible via xml:
+```lua
+local mainFrame = basalt.createFrame():addLayout("example.xml")
+
+basalt.setVariable("checkboxChange", function(self)
+  local checked = self:getValue()
+  basalt.debug("The value got changed into ", checked)
+end)
+```
+
+```xml
+<checkbox onChange="checkboxChange" />
+```
+