The variables are local now, which makes them being handled correctly
when calling `autoenv_source_parent`.
Without this, a call to `autoenv_source_parent` overwrites the values in
the current scope.
This changes the defaults:
- AUTOENV_FILE_ENTER: .env => .autoenv.zsh
- AUTOENV_FILE_LEAVE: .env_leave => .autoenv_leave.zsh
`.env` is usually used only for key-value pairs for environment
settings, e.g. with foreman. We do not want to interfere with this.
This also renames the setting/variable AUTOENV_ENV_FILENAME to
AUTOENV_AUTH_FILE, and uses the [XDG
spec](http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html#variables)
for the default location.
The new default location for the auth file will be
~/.local/share/autoenv_auth.
When the old setting is used, or the previous default exists, a warning
is given with instructions.
Fixes https://github.com/Tarrasch/zsh-autoenv/issues/31.
Closes https://github.com/Tarrasch/zsh-autoenv/pull/32.
- Support for leave event, via DOTENV_FILE_LEAVE and _dotenv_event (can
use DOTENV_FILE_LEAVE=$DOTENV_FILE_ENTER).
- Support for searching upwards for $DOTENV_FILE_ENTER (#3).
- Source .env only once per session, but re-source when leave events
are enabled (#1).
- Trigger the machinery when the script gets sourced, for the current
dir (#2).
