Refactored and prepared erlog for production use

* got rid of passing functions everywhere. Maybe it is little bit faster, but code is hard to maintain. Refactored erlog gen_server, made erlog logic more OTP like: now there is one function to call - execute and all work is done through handle_call. Server state (db and others) is kept in #state of gen_server.
* refactored erlog_int, got rid of defining code (as from my point of view it is not good way), move storage functions from erlog_int to callback interface, made callback interface realisation for ets and dict (dict not working properly for now).
* created erlog_memory - gen_server, which works with memory (dict, ets, database, and others implementation). There is no need to pass db param as argument everywhere in code. It is stored is #state of erlog gen_server. (But I don't remove passing db in some places, as there are lots of them).
* moved all modules to folders
* moved functions from huge (500+ line of codes) modules to smaller one
* erlog_int -> erlog_memory, erlog_core