Add Lua compiler

Redbean Lua Server Pages may now be stored in the zip as byte code. This
can improve performance, since redbean currently doesn't cache byte code
but it might be more useful for anyone wanting to create a closed source
redbean. The .lua extension should be used for byte code files. Lua will
tell them apart based on a magic number at the start of the file.

This change also improves some Lua error reporting conditions. See #97

third_party/lua/README.cosmo

@@ -1,3 +1,26 @@
-origin https://github.com/lua/lua/
-commit c03c527fd207b4ad8f5a8e0f4f2c176bd227c979
-date   Mon Feb 15 13:31:45 2021 -0300
+DESCRIPTION
+
+  Lua is a language designed for embedded use in native applications. It
+  has an impossibly elegant C API and the Lua language itself feels more
+  like Python compared to alternatives like Tcl except it's a great deal
+  faster and doesn't have strong opinions about character encoding.
+
+PROVENANCE
+
+  https://github.com/lua/lua/
+
+  commit e7803f7dbcdc966ab1f9db143424ee811ab1a398
+  Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
+  Date:   Wed Mar 3 09:44:20 2021 -0300
+
+      New release number (5.4.3)
+
+  luac.c needed to be sourced from:
+  https://www.lua.org/ftp/lua-5.4.3.tar.gz
+
+LOCAL MODIFICATIONS
+
+  The `\e` string literal escape sequence has been added, which is
+  equivalent to `\27` (the Lua version of `\033`) or the ASCII ESC
+  character. It may be used for teletypewriter control like having
+  bold text, which can be encoded elegantly as `\e[1mHELLO\e[0m`.