Merge pull request #124 from corliss/dev2

A number of fixes and tests added this week :)
Add Container.Remove(Control child) abstract method to remove a child regardless of the type of container
Add Control.RemoveFromParent() convenience method to remove a control from its container
Split out DockContainer to its own file
Cleanup
WinForms: Fixes to layouts
WinForms: Leak fixes for GridView/NumericUpDown
Wpf: Fixes for recent layout refactoring and ever expanding scrolling regions
WinForms: Add missing file
Update and cleanup Eto.Test
Rename Splitter.SplitterMoved event to PositionChanged to match Position property and associated Changed event
Cleanup some controls and remove un-needed handler instance
Mac/XamMac: Use weak references from NSObject-based objects back to eto or other objects.
Mac: Update SearchBox/TreeGridView/TreeView to reference handlers in weak
Fix compile error from merge
Unbind is only necessary when disposing explicitly
Add SearchBox implementation for Gtk/Wpf
WinForms: SearchBoxHandler can use TextBoxHandler implementation
RowsSection is really a test of the TableLayout with default ending column/row scaling
ComplexLayoutSection is really a test of the Splitter
Eto.Test Sections should not be responsible for where the content goes, as this ties the MainForm implementation to the section list too closely.
WindowSectionMethod now shows a button to open the window/dialog, as opening them automatically is too jarring
AnchorSection should now work, as you need to set the position of the children when the control is loaded and when the size is changed, not before.
Add missing SearchBoxHandler.cs to Gtk/Wpf projects
Mac: Optimize colouring of controls
Mac: Fix TableLayout for adjusting space of the last row/column when they are scaled by default
Mac: TableLayout will now repaint children that were previously obscured to ensure they are drawn, when their frame doesn't change
Mac: Fix auto sizing of Grid columns when scrolling and expanding items in the TreeGridView
Mac: Clean up getting the handler instance from overridden methods