Shell rewrite

[khale]

This PR introduces some major changes to the shell. The most significant change (in f31ebb777e3ac227feb014d614940ec427db6670) makes it so that shell commands no longer need to be added to shell.c. Rather, the handler and the registration can all be in the subsystem of interest.

Some other bells and whistles added in this PR include:

• better help command with longest prefix matching. e.g. with the command: $> pci dev bus slot fun the help command understands $> help pci and will print out the help string associated with that command. $> help p will print the help string for every available command that matches the string p.

• new history command, also with LPM.

  • $> history <- prints out most recent history
  • $> history 2 <- prints out the 2 most recent history items
  • $> history pc <- prints out all recent command invocations which match the string pc

• fish-style autocompletion at the shell. As you type at the shell, the shell will predict commands based on your history. You can hit <TAB> to accept the suggestion, followed by <ENTER> to run it.

[khale]

This pull request introduces 1 alert and fixes 2 when merging f252927fdce8c8da0e53ffd916190d200d05f84a into 3fb088b137a99437742da4953fd57f0a94097ac5 - view on LGTM.com

new alerts:

• 1 for Function declared in block

fixed alerts:

• 2 for Function declared in block

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Comment posted by LGTM.com