- add ExpandedHeight property for ExpandCollapsePanel
- edit size child controls in Demo app form
- remove unnecessary usings
- add Classic ExpandButtonStyle
- add Small ExpandButtonSize
- panel animation functionality on expanding or collapsing
- comments
Merge branch 'develop' of github.com:alexander-makarov/ExpandCollapsePanel into develop

Conflicts:
	ExpandCollapsePanelDemo/Demo.Designer.cs