Set WORDCHARS in the editor module
[Fix #419] start gpg-agent also with ssh-support off

and add a note on the variables exported by this module
Enhanced section on exported variables in the README
replace gpg-agent check to work on *NIX & *BSD, too
Add additional `grep` cmd.

This is necessary to ensure that the `PID` found in `$_gpg_env`
actually belongs to `gpg-agent` and not some other process.
Merge branch 'gpg-agent'

Conflicts:
	modules/gpg-agent/init.zsh