Can't run nimble commands from sub directories of the project.
When I am in the subdirectroy of my project, for example in my [examples directiory](https://github.com/krux02/opengl-sandbox/tree/master/examples), then I can't execute any nimble commands. For that I have to be in the top directory that contains the nimble file.

```
$ nimble compile ./hello_triangle.nim 
     Error: Specified directory (/servers/krag/hdd-home3/doering/proj/nim/fancygl/examples) does not contain a .nimble file.
$ cd ..
[...]
Success: Execution finished
```

This makes it very painful to work in projects with a deeper directory hierarchy. I always have to be in the top directory of the project to be able to execute nimble commands.  Also emacs integration is a pain. By default a file that is opened in emacs puts the emacs process in that directory. Emacs is therefore always in the directory of the file it operates on. It is possible to change this behavior, but a lot of plugins and tools written in emacs assume this behavior and changing it will therefore cause a lot of problems. Therefore when I want to run a nimble task from a file [buffer](https://www.gnu.org/software/emacs/manual/html_node/emacs/Buffers.html), I need to be able to start that nimble task from the directory of that file.