Rework transaction functions (Part 1)

• Move CommandLine parsing function in tx.py file.
• Check that the output pubkey format is good and the comment is good before displaying the resuming transaction chart

Enough for this release. New rework tasks will be for next release: https://github.com/duniter/silkaj/issues/72.

changed title from Rework transaction functions (1/2) to Rework transaction functions (Part 1)

mentioned in issue #72 (closed)

added D: Transfer label