Updated readme and fixed some small bugs.

Merge cursor style

Improved Styles

Implemented WidgetProps over the unit type ('()') so that widget's
without the need for props can be defined without them

Methods made pub as they may be useful in certain scenarios

Added StyleProp::select helper method

This also seems to have fixed a bug that caused the textbox to jump when
focused (?)

Fixed crashes when no context existed.

- Text refusing to size correctly
- Fonts not loading correctly with new bevy context.

Added border color to styles.

[RFC 1.1] Widget Restructuring

`OnEvent` now takes `KayakContextRef`