This change allows providing a custom template arg flag -t/--template:
```
sinol-make init foo -t [repo link or disk path] [optional subdir]
```
It defaults to the upstream repository and example_package subdir.

Changed the example_package id pattern from `abc` to `__ID__`.
All filenames and file contents are now substituted.

Changed the positional output directory argument to `-o/--output` flag
to help avoid accidents.

Added result directory cleanup on failure.

Try accessing the local git repo in the project root first when cloning
example_package. Only if that doesn't work, fall back to online github.

Also adds some extra local path tests to init/test_unit.
Also removes one unnecessary os.getcwd() call.
Also removes the old "abc" template string hack since we test the
current template now.