guilib: add input validation functionality to CGUIEditControl
settings: implement input validation for edit controls
CGUILabel: introduce <invalidcolor> support
smartplaylists: add support for input validation
[confluence] add <invalidcolor> for edit controls and in SettingsCategory.xml
[confluence] support invalid input in SmartPlaylistRule.xml
[win32] update VS project files
[osx/ios/atv2] - sync xcode project
Merge pull request #3088 from Montellese/gui_input_validation

CGUIEditControl: add input validation