~/.sysl breaks module root discovery

[anzdaddy]

Please do not post any internal, closed source snippets on this public issue tracker!

Description

The name .sysl is being used for two different purposes

1. The ~/.sysl directory is where Sysl caches stuff.
2. A .sysl sentinel entry in a repo denotes the root of a sysl module.

Since practically all users work with repos under their home directory, these two purposes are almost certain to come into conflict.

Steps to Reproduce

1. Ensure that ~/.sysl is present.
2. sysl pb --mode=json somefile.sysl | grep file

Expected behavior

...
          "file": "./somefile.sysl",
...

Actual behavior

...
          "file": "a/path/relative/to/my/home/directory/somefile.sysl",
...

Your Environment

$ sysl info
Build:
  Version      : v0.185.0
  Git Commit   : 2a486a10550284976d08a7002d0f7b296a45da6e
  Date         : 2020-08-16T10:25:55Z
  Go Version   : go1.14.3 linux/amd64
  OS           : linux/amd64

[anzdaddy]

A partial fix is use .git as a hard stop. If no .sysl has been found, but .git has, then a root is not defined.

The long term fix is to rename ~/.sysl. Perhaps ~/.sysl-cache, though future uses might render that suboptimal.