One namespace per flutter directory rather than one per file

[JeroMiya]

Currently the transpiler creates a new namespace for each file rather than the directory it's in. Maybe it should be an option, but I think it would be better to just have one namespace per directory.

Example, instead of this:

using FlutterSDK.Widgets.Pages;
using FlutterSDK.Widgets.Performanceoverlay;
using FlutterSDK.Widgets.Automatickeepalive;
using FlutterSDK.Widgets.Scrollcontroller;
using FlutterSDK.Widgets.Widgetinspector;
using FlutterSDK.Widgets.Icon;
using FlutterSDK.Widgets.Scrollcontext;
using FlutterSDK.Widgets.Inheritedmodel;
using FlutterSDK.Widgets.Annotatedregion;
// etc...

Just this:

using FlutterSDK.Widgets;

Of course, this may result in name resolution issues, so close this issue if that happens in the flutter namespace itself (I don't believe it does).