remove optimisation to ArrayType#write - this code is only used to write undolog entries, which hardly ever hit disk anyway

Because of how we are storing the min-max-flag in the read/write method the no. of dimensions must be <= 31.

Issue 548: TO_CHAR does not format MM and DD correctly when the month or day of the month is 1 digit, patch from "the.tucc"

An archive tool that uses compression and de-duplication (compresses better than 7zip / pkzip for large directories in many cases)

MVStore: support two compression levels; measure read and written bytes; ascending iteration over entry set