Add --global (-g) flag

[andreynering]

This is an idea that has been in my mind for some time. Feedback and/or suggestions are welcome.

In short, this adds the ability to run a Taskfile from your home directory ($HOME/Taskfile.yaml), meaning that you can now have a Taskfile that you can run from anywhere with a simple task -g ....

[pd93]

I don't see a downside to this. Its simple and I'm sure lots of people will find this useful.

Worth noting that you can get this behaviour today by putting a Taskfile in $HOME and running task (without -g) if there are no other Taskfiles between $PWD and $HOME. However being able to call it from inside a project containing a Taskfile is super useful.

Its a little difficult to make tests for this since it relies on os.UserHomeDir(), but its also quite simple code - so maybe we don't need one? We could mock out the call to os.UserHomeDir though if you think its worth it.

[andreynering]

Thanks for your comments @pd93.

The fact is that we don't have any test for cmd/task/task.go at the moment. Perhaps someday we could try extract some behavior out of the main package and write a few simple tests.

And yes, -g is useful because you can run even when the current directory has another Taskfile.