Support pwqgen/pwgen checking

Closes #66.

abra

@@ -306,6 +306,18 @@ fi
 
 ###### Safety checks
 
+require_pwqgen() {
+  if ! type pwqgen > /dev/null 2>&1; then
+    error "pwqgen program is not installed"
+  fi
+}
+
+require_pwgen() {
+  if ! type pwgen > /dev/null 2>&1; then
+    error "pwgen program is not installed"
+  fi
+}
+
 require_abra_dir() {
   mkdir -p "$ABRA_DIR"
 }
@@ -819,8 +831,10 @@ sub_app_secret_generate(){
   LENGTH="$abra__length_"
 
   if [[ "$SECRET" == *"password"* ]]; then
+    require_pwqgen
     PWGEN="${abra__cmd_:-pwqgen}"
   else
+    require_pwgen
     PWGEN=${abra__cmd_:-pwgen -s "$LENGTH" 1}
   fi