edit database format  — one file per key, first steps to big key-value storage (turn off cache = disk storage)
tests update
test dir added
readme update
all operations in database — in filesystem, to optimize queries — using cache, still without memory usage limit
database cache  with approximate memory usage count
test support functions (like folder remove) — in separate object
rework architecture
Store table in one file on disk.  implement CRUD (Known issue: sometimes crashed on update). No restore at the moment. Could add data until have RAM to store index — (key, long) values
fixed cache bug (which caused crash on update operation)
readme update
tests, refactor