Allow passing MaxChar to Rex::Ui::Text::Table cols

Passing MaxChar allows setting the maximum number of characters
printed within a specific column during the row_to_s method.
This does not affect CSV output nor truncate the actual data.
Meant for tidying up long console ouput.

Example: cleaned up cmd_creds to show proof and not maul tables
with unix session data.
Allow selection (and ordering) of column names

Build the creds table with only the columns we select,
in the order selected.

Example:

creds -s ssh -u root -S pubk -c port,user,proof

Credentials
===========

port  user  proof
----  ----  -----
22    root  KEY=30:...
22    root  KEY=37:...
22    root  KEY=30:...
22    root  KEY=37:...
22    root  KEY=a6:...
22    root  KEY=30:...
22    root  KEY=37:...
22    root  KEY=a6:...
22    root  KEY=30:...
22    root  KEY=37:...
22    root  KEY=a6:...
22    root  KEY=30:...
22    root  KEY=37:...
22    root  KEY=a6:...
22    root  KEY=30:...
22    root  KEY=37:...
22    root  KEY=30:...
22    root  KEY=37:...
22    root  KEY=a6:...
22    root  KEY=30:...
22    root  KEY=37:...
fix copypasta
Merge for retab
Retab changes for PR #2093
Merge pull request #7 from tabassassin/retab/pr/2093

Retab/pr/2093
Clean use of -c on creds command
Land #2093, @sempervictus MaxChar for Rex::Ui::Text::Table cols
Fix db_spec
Land #2654 which fixes rpsec for #2093