Mnapi 1.2

I tweaked a bit my Java/PHP API for Mnesia by adding memory caching for auxiliary table structures used by the API. My tests have shown that it speeds up fetching single rows for tables where data are kept in disc_only_copies by about 2%. Much less than I expected, I must say. But since the changes are really little and work seamlessly with data created with Mnapi 1.1 and earlier, I decided to leave them in the code. If anyone is interested in the new version, here it is.