flutter_package / fluttertpc_get

[docs] BindingBuilder documentation, refactor in dependency management docs

[docs] Change "namedRoutes" for "GetPages" in docs

Create internationalization.md

This is a very basic documentation to getting started with internationalization with getx.

Fix missing .obs for list and map

Fixes and features

- Change GetPageBuilder to WidgetCallback typedef, so we can use it outside Get and the name makes more sense.
- Added isDesktop/isMobile
- Added GetPlatform (web) getters to detect the OS it runs (using navigator UA)
- Added nil extension (can be useless now), to enforce the null type safety in JS for old dart2js versions (was undefined)

Missing code block end mark fix in README.pl.md