v2.7.0 released (C4 styled Sequence diagram)

[kirchsth]

It is time for a new release v2.7.0!

The 2 new main features are

• (C4 styled) Sequence Diagram support
• Sequence/Dynamic diagram - simplified to "one" Rel() call
  • Sequence diagram (Rel() extended with $index, $rel; replaces RelIndex() and RelSpecialIndex())
  • Dynamic diagram(Rel() extended with $index; makes all RelIndex...() calls obsolete)

I hope you like it