Deprecate transaction type NORMAL

[kroggen]

Proposal:

• Put in the documentation that the transaction type NORMAL is deprecated and should be avoided
• Update all our client applications and wrappers (hera, libaergo...) to not use NORMAL transactions

The backwards compatibility brings many problems, so lets at least decrease the use of this type of transactions. Then later (some years?) we can remove support for them.

For simple payload check #144