Commands improvement

[ChrisVilches]

One way to improve the usage would be:

term_keep # show all

term_keep 14 # show ID = 14

If you implement this, make sure:

• The command help makes sense.
• Command names and arguments make sense (for example, it can no longer be called show all because it has the new optional argument). Maybe it could simply be called display and the optional argument ID is for displaying only one, or if it's not present, show all.
• The current show command is no longer appearing (or perhaps it could be an alias).
• There are some other things that probably would need to be fixed, or taken care of.