debugger

A simple, highly embedabble CLI debugger for Lua 5.x, and LuaJIT 2.0.

Features:
* Simple installation as either a single .lua file (< 500 LoC) OR a single .c/.h file pair.
* Drop in xpcall() and lua_pcall() replacements that drop into the REPL for an error.
* Optional colored output and GNU readline (LuaJIT) support.
* Extendable I/O that defaults to stdin/stdout.
* Simple assert style breakpoints.
* REPL with step, next, finish, print/eval, up/down, backtrace and list locals commands.
* Pretty printed output for tables.
* Speed! Debug hooks are only set when stepping and do not otherwise affect performance.