Support to zsh

Hi ​@mcunha 

Here is a super unofficial, hacky and totally not tested solution:

Open venv/bin/activate in an editor and adapt the following two functions.

_AX_set_env() {
  # Must be called before defining deactivate function
  local var="_OLD_ENV_${1}"
  local x=
  # Check if deactivate function exists (bash/zsh compatible)
  local deactivate_exists=0
  if [ -n "${BASH:-}" ]; then
    type deactivate &>/dev/null && deactivate_exists=1
  else
    typeset -f deactivate &>/dev/null && deactivate_exists=1
  fi
  # Indirect variable expansion for bash and zsh
  if [ -n "${BASH:-}" ]; then
    if [ -n "${!1:-}" ] && [ $deactivate_exists -eq 0 ] ; then
      eval "${var}=\"${!1}\""
    fi
  else
    # zsh indirect expansion
    if [ -n "${(P)1:-}" ] && [ $deactivate_exists -eq 0 ] ; then
      eval "${var}=\"${(P)1}\""
    fi
  fi
  # strip escapes from $ expressions and evaluate RHS before assigning to LHS
  x=${2//\\\$/\$}
  x=`echo $x`
  eval "$1=\"$x\""
  export "$1"
}

for _AX_var in "${_AX_envs[@]}"; do
  if [[ "$_AX_var" == *=* ]]; then
    _AX_set_env "${_AX_var%%=*}" "${_AX_var#*=}"
  fi
done
unset _AX_var

_AX_reset_env() {
  local var="_OLD_ENV_${1}"
  if [ -n "${BASH:-}" ]; then
    if [ -n "${!var:-}" ]; then
      eval "$1=\"${!var}\""
      export "$1"
      unset ${var}
    else
      unset $1
    fi
  else
    # zsh indirect expansion
    if [ -n "${(P)var:-}" ]; then
      eval "$1=\"${(P)var}\""
      export "$1"
      unset ${var}
    else
      unset $1
    fi
  fi
}