Editable HighlightView Implementation

[tusharsadhwani]

Expands on the implementation in PR #13

• Adds a controller property to HighlightView, so people can provide text via text property or via controller property

• Add an editable property, which if true, renders a TextField instead of a RichText

• Updated the example to use editable HighlightView

Fixes #3
Fixes #6

[tusharsadhwani]

@dutrieuc @pd4d10 thoughts?

[dutrieuc]

Seems good to me !

[waf]

I've used @tusharsadhwani's branch in a small side project of mine, and it's working beautifully! It'd be good to get this merged. 👍

[tusharsadhwani]

Since this project seems kinda abandoned, and since the subdirectory-based structure of this repo doesn't let you directly add a fork's github URL in your pubspec.yaml to modify and use this project, I've taken the liberty of copying the flutter_highlight part of this repo into my own (although I have credited the original).

You can use my fork in your projects by doing this in your pubspec.yaml:

dependencies:
  flutter:
    sdk: flutter
  highlight: ^0.6.0
  flutter_highlight:
    git: https://github.com/tusharsadhwani/flutter_highlight