Add a new expand_tilde() function that performs tilde expansion of
strings, and corresponding unit tests:
* A ~ at the beginning of a path is expanded to the user's home
directory.
* Literal '~' can be provided with '\~'
Combine this with expand_environment() in a new expand_filepath()
function which applies all (both) required expansion functions to a
string, and use that in get_config_file_options() to expand .stowrc
options.
Add more tests to check that tilde expanded in correct places, i.e.:
* expanded for --target and --dir
* not expanded for --ignore, --defer, or --override
Update documentation on stowrc files according to this functionality
change.
Fixes#14: https://github.com/aspiers/stow/issues/14
dc42c34107