factor.sh: Allow bootstrap on other branches for commands that don't pull from git.
io.streams.peek: Implement peek and peek1.
io.streams.peek: use namespaces.
compiler.tree.propagation.known-words: adding known outputs for some words.
Revert "compiler.tree.propagation.known-words: adding known outputs for some words."

This reverts commit 16d8e6555b9f82ec55bbb9f9e57ad638bae04b7c.
compiler.tree.propagation.known-words: retry this change, some issue with use vocabs.
math.functions: adding "round-to".
twitter: Update API url.
unix.linux.proc: Add a parser for some of the /proc and /proc/[PID]/ files.
unix.ffi: Add the man 2 signal() function call.
debugger.unix: Get the signal name from a signal object too.
debugger.unix: Make this vocab unix only.
io.backend.unix: Nobody uses (refill), remove it.
math.statistics: Add docs for collect-by and collect-index-by.
rosetta-code.top-rank: Use collect-by instead of defining it as group-by.
math.statistics: adding z-score.
factor.sh: Allow bootstrap on other branches for commands that don't pull from git.

 Merge from slavs.
Merge branch 'clean-macosx-x86-64' of github.com:slavapestov/factor into davec
Modified hex dump to use groupings other than 1 byte.
Added redwords to syntax parsing.
Added deprecated to syntax highlight.