Write more redbean unit tests

- Fix DescribeSigset()
- Introduce new unix.rmrf() API
- Fix redbean sigaction() doc example code
- Fix unix.sigaction() w/ more than two args
- Improve redbean re module API (non-breaking)
- Enhance Lua with Python string multiplication
- Make third parameter of unix.socket() default to 0

test/tool/net/lua_test.lua

@@ -0,0 +1,21 @@
+-- Copyright 2022 Justine Alexandra Roberts Tunney
+--
+-- Permission to use, copy, modify, and/or distribute this software for
+-- any purpose with or without fee is hereby granted, provided that the
+-- above copyright notice and this permission notice appear in all copies.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+-- WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+-- WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+-- AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+-- DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+-- PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+-- TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+-- PERFORMANCE OF THIS SOFTWARE.
+
+-- test redbean lua language extensions
+assert(0b100 == 4)
+assert(0200 == 128)
+assert("\e" == "\x1b")
+assert("hi" * 3 == "hihihi")
+assert("hello %d" % {123} == "hello 123")