* add new dotfile function `dotspacemacs/user-env`
* add ignored env. vars with variable spacemacs-ignored-environment-variables
* ignore env vars: SSH_AUTH_SOCK and DBUS_SESSION_BUS_ADDRESS
* update documentation in DOCUMENTATION.org
* update .spacemacs.template with new function
* rename environment file from spacemacs.env to .spacemacs.env
* move location of .spacemacs.env file to home or dotdirectory
* add a header to the generated .spacemacs.env file to explain what it is
* make SPC f e e fallbacks to the function dotspacemacs/user-env if the user
manages the env var by themselves
* make SPC f e E call the new function dotspacemacs/user-env
* sort environment variables in .spacemacs.env file
See updated DOCUMENTATION.org and FAQ.org for more info.
* add core-env.el
* add library load-env-vars.el
* add bootstrap package dotenv-mode.el
* remove spacemacs-environment from bootstrap layer
* remove dotspacemacs variable dotspacemacs-import-env-vars-from-shell
* remove dotspacemacs variable dotspacemacs-improt-env-vars-shell-file-name
* add new key binding SPC f e e to open spacemacs.env file
* add new key binding SPC f e E to reload environment variable from env file
* add new key binding SPC f e C-e to re-initialize the env file from shell.
