`gsh config` command

[phyver]

Just an idea: a command to configure a couple of things:

• no_color or a way to change colors for success / failure
• pager
• quiet option
• verbose option (in debug mode only)
• no_parchment option
• encoding (if we indeed use it, see Find a way to deal with UTF-8 with old awk versions #24)
• no_progress_bar or similar option