This consolidates all of the non-template .gitignore rules into the top level .gitignore, to ignore common things more broadly, with less maintenance needed for the .gitignore files. Does not touch the templates, so that they still produce needed .gitignores as part of flutter create.
* wip
* wip
* delete main.m
* readd main.m
* update to use new channel api
* update android
* removed android/
* remove debug print
* remomved main.m
* Update year in copyright
* break long line and update name
* mit comments
* update examples/README
* break line
* update README
* update test