Add high level prompting to Terminal.

This is a breaking change to the Terminal methods Password and Prompt(now
GetPassword and GetPrompt) to fix a naming conflict with the higher
level method Password.
Move output files to buffer.
Add history support to Terminal.

This support is set to the up/down arrows like Readline uses. It tries
to keep similar functionality and copies the history item when the
content is edited to the current items index.