Fix iOS plugin SetMargins

* Fix SetMargins for Landscape mode.
* Additional SetFrame function so the window can be set from a center point and size.
iOS: add SetFrame function
webview object: add SetCenterPositionWithScale for iOS and Mac
Merge pull request #13 from endavid/fix/iOSLandscape

Fix iOS plugin SetMargins
Check if the keyboard is active from the Webview plugin

* Unity's TouchScreenKeyboard.visible always returns false on Android when the keyboard is active from the plugin.
* With this fix, you'll be able to know when the soft keyboard has been opened in Android.
* For other platforms, it will just default to Unity's TouchScreenKeyboard.visible
Merge pull request #14 from endavid/feature/isKeyboardVisible

Check if the keyboard is active from the Webview plugin
Update to Android SDK 18 (4.2)
Allow cross-origin access from local HTML files
Enable localStorage
Update README.md
Add console.log() printouts to logcat
Fix sending messages from WebView to Unity code in Android 4.2 and up
Fix crash in Android 4.0.x and earlier
Allow redirecting to custom scheme URLs on Android
Merge commit '6f64e9db339305f892082a69a1cb200ae594d30d'

Conflicts:
	plugins/WebViewObject.cs
Merge pull request #1 from privman/master