Fix weird repl scoping issue.

This would cause locals-saving in the repl to not work on certain
things because the second reference would be considered a clash and
get mangled to have a zero on the end in the compiled output.

See https://todo.sr.ht/~technomancy/fennel/85
Fix comment special to work with strings that have newlines in them.
Re-word "unknown global" to "unknown identifier".

It might not be a global; it could be a misspelled local.
Tidy up some repl things; add commented out failing test case.
Optimize icollect using var+set.

There is a pretty significant performance boost by tracking length
ourselves instead of calculating it afresh on every insert. For
details see https://p.hagelb.org/icollect-performance.html
Add values document.
Reword readme claim.
use FENNEL_SRC env variable when building fennel
Add example for defining a function in a table.
Merge branch 'allow-renaming-native-modules-in-compile-binary' of github.com:Benaiah/Fennel
Calculate allowed globals based on compiler sandbox.

Previously we were erroneously calculating it based on the
non-sandboxed runtime globals, oops! This led to some confusing errors
where we would get nil for globals which weren't in the sandbox.
Be more tolerant of weird Lua implementations.

We have a report from someone using gopher-lua which apparently is
completely missing package.config and errors out when you call the
string.gmatch iterator directly. This might work around the problems
they saw.
add --rename-native-module example to --compile-binary --help
use match instead of if to declare require-name in binary.fnl
use utils.copy in binary.fnl
fix tables with negative arguments being treated as sequential
Make repl default to serializing with fennelview.

Before this you had to pass it in explicitly for some reason; didn't
make much sense.
Explain macro searchers in api.md.

In particular, show how to load C modules inside macros when the
compiler sandbox is not needed.
remove --rename-native-module from args after handling it
allow renaming native modules in --compile-binary