MVStore: encrypted stores are now supported - avoid creating many objects during all operations, specially PBKDF2

Patch by lukas.eder@gmail.com

Optimize IN(...) queries: there was a bug in version 1.3.170 for comparison of the type "X IN(NULL, NULL)". Fixed.

Timestamps with timezone that were passed as a string were not always converted correctly. For example "2012-11-06T23:00:00.000Z" was converted to "2012-11-06" instead of to "2012-11-07" in the timezone CET.