This API should be simple.
Each module should collect statistics and stores them internally, preferibly
in a table format because this is how Admin will expect the results.

Each module should implement 2 functions:
- stats_get_tables_list() returns an array of pointer to variables name, where
  the last element is NULL;
- stat_get_table() returns the content of such table in the form of a
  SQLite3_result resultset


Important note:
The reads should be considered in read committed isolation level. It is not
possible to read multiple tables at the same time, therefore it is possible
that the relation between these tables are not consistent. Due the temporary
nature of statistics information, this glitch is absolutely expected.