A little cleanup and clarity

ScreenManager Release v1.1.0

• Some superfluous <template>s were removed from the register external screen API
• Some methods now marked as const (thank you @kfoltman for guidance)
• Clarified some wording and added a little history

Full Changelog: v1.0.0...v1.1.0

Initial Release

The ScreenManager Library

This is the first release of lightweight C++ library for managing application screens, navigation, transitions and display timing.

It is platform, framework and GFX agnostic - no dependencies on anything and no std lib.

Written because there doesn't seem to be anything that does this cleanly, without imposing a whole bunch of classes into your app. This requires only the implementation of a single simple lifecycle interface for Screens and an entirely optional single method interface for Routers.

Full Changelog: https://github.com/Stutchbury/ScreenManager/commits/v1.0.0