**** Author : tanjie(tanjiesymbol@gmail.com)
**** Date : 2013-07-01
**** Desc : this is a gdb-like debug tools for lua
**** Usage :
1.require("ldb")
2.ldb.ldb_open() --you will pause here for setting breakpoints
3.ldb.ldb() --set breakpoint anywhere you want to pause
4.b/bd/be/bl --add/disable/enable/list the breakpoints
5.p/print --print local or global variables
6.s/step --step into a function
7.n/next --step over a function
8.l/list --list ten lines around the current line
9.f/file --print the current file and line number
10.bt --print traceback
11.c/cont --continue
12.set --set the value of local or global