[iso_build.sh] Review and added new features

* Add SABAYON_EXTRA_PKGS variable for add custom
    packages on building without review specs file
    (for development tests)

  * add option --only-dev

  * integrate installation of enman repositories.
    Currently this operation is done on sources chroot.
    To move as plugin of molecule.

  * add option for unmasking of packages through
    SABAYON_UNMASK_PKGS

  * Add option --skip-docker-rmi

scripts/remaster_generic_inner_chroot_script.sh

@@ -4,22 +4,22 @@
 . /etc/profile
 
 safe_run() {
-	local updated=0
-	for ((i=0; i < 42; i++)); do
-		"${@}" && {
-			updated=1;
-			break;
-		}
-		if [ ${i} -gt 6 ]; then
-			sleep 3600 || return 1
-		else
-			sleep 1200 || return 1
-		fi
-	done
-	if [ "${updated}" = "0" ]; then
-		return 1
-	fi
-	return 0
+  local updated=0
+  for ((i=0; i < 42; i++)); do
+    "${@}" && {
+      updated=1;
+      break;
+    }
+    if [ ${i} -gt 6 ]; then
+      sleep 3600 || return 1
+    else
+      sleep 1200 || return 1
+    fi
+  done
+  if [ "${updated}" = "0" ]; then
+    return 1
+  fi
+  return 0
 }
 
 # make sure there is no stale pid file around that prevents entropy from running
@@ -28,8 +28,8 @@ rm -f /run/entropy/entropy.lock
 FORCE_EAPI=2 safe_run equo update || exit 1
 
 for repo in $(equo repo list -q); do
-	echo "Optimizing mirrors for ${repo}"
-	equo repo mirrorsort "${repo}"  # ignore errors
+  echo "Optimizing mirrors for ${repo}"
+  equo repo mirrorsort "${repo}"  # ignore errors
 done
 
 exit 0