Add an option to enable ldb

Check out http://github.com/laarmen/lua_debug to get the software
Patches welcome!
Add an @prefix to the chunk sources to more or less match the original Lua nomenclature
#1734  UI: speeding up the buy and sell process in the marketplace
Merge remote-tracking branch 'laarmen/lua_debug'
Merge pull request #2188 from UncleVasya/buy_sell_speedup

#1734  UI: speeding up the buy and sell process in the marketplace