6.0.16-lua-enhancement-20220522-beta

1. let lua bigdecimal round() accept type bigdecimal userdata, lua string, or lua number for first argument.
2. remove unnecessary lua_pop() operations.

6.0.16-lua-enhancement-20220517-beta

FIX:

1. bigdecimal.new() as zero without argument.
2. VpFree() double free issue.
3. digit_leader() return char type.

6.0.16-lua-enhancement-20220516-beta

1. add lua bigdecimal function power(), __add, __sub, __mul, __div, __unm, max_length(), cur_length(), effective_digits().
2. let negate(), abs() return a new bigdecimal instance.

6.0.16-lua-enhancement-20220502-beta

• support lua module script
• add lua bigdecimal package