Refactor persist.save_from_table
Refactor persist.save_from_table

* Update docstrings;
* Improve string quoting (don't produce broken code for strings with
backslashes);
* Use same function for writing keys and values;
* Don't use same name (write_table) for two different functions.

robooo/luarocks,tst2005/luarocks,ignacio/luarocks,keplerproject/luarocks,tarantool/luarocks,coderstudy/luarocks,xpol/luainstaller,keplerproject/luarocks,xpol/luavm,usstwxy/luarocks,luarocks/luarocks,ignacio/luarocks,usstwxy/luarocks,tarantool/luarocks,tst2005/luarocks,luarocks/luarocks,lxbgit/luarocks,robooo/luarocks,xpol/luavm,aryajur/luarocks,xpol/luavm,rrthomas/luarocks,coderstudy/luarocks,xpol/luarocks,aryajur/luarocks,xiaq/luarocks,usstwxy/luarocks,rrthomas/luarocks,xpol/luavm,xpol/luarocks,tarantool/luarocks,usstwxy/luarocks,starius/luarocks,robooo/luarocks,aryajur/luarocks,ignacio/luarocks,xpol/luarocks,tst2005/luarocks,rrthomas/luarocks,xiaq/luarocks,ignacio/luarocks,xiaq/luarocks,keplerproject/luarocks,coderstudy/luarocks,xpol/luavm,robooo/luarocks,starius/luarocks,xpol/luainstaller,xpol/luarocks,lxbgit/luarocks,lxbgit/luarocks,starius/luarocks,rrthomas/luarocks,xpol/luainstaller,xpol/luainstaller,lxbgit/luarocks,tst2005/luarocks,coderstudy/luarocks,aryajur/luarocks,luarocks/luarocks,starius/luarocks,keplerproject/luarocks,xiaq/luarocks