develop
Make VariantValueArray as readonly struct
Get rid of ImmutableHashSet, refactor cache key code
Allow to select from CLR enumerables
Fix incorrect schema detection bug with gzip files
Replace CommandHandler by IFuncUnit
Create Core module, move main classes there
Refactor query context, separate into input and query part
Add more code comments
Move ErrorCode to Core namespace
Make column index one-based
Use column index instead of column name to set key
Add web server simple files serve support
Allow to set up application culture