The program has become stable with the new rustyline code base.

New Features

• two suggestion modes: list & hint
• use the configured exec_cmd to launch header_cmd and cheat sheet
• add interface.suggestion_spacing to pad empty lines between input field and suggestion list
• add helper scripts

Bug Fixes

• clear screen before module.cmd execution, so that otter-launcher stdout wont flash back
• fix header_cmd misbehavings
• fix tab-completion misbehavings