The statement "shutdown defrag" now compresses the database (with the MVStore). The MVStore now automatically shrinks the file in the background if there is no read or write activity. This might be a bit too aggressive; feedback is welcome!

improve some method names, and make the call to convert ValueArray to a SearchRow just pass in a ValueArray, since it makes the call sites easier to read

Gives a better out of box experience for people with more powerful machines.

change default value of PAGE_SIZE from 2048 to 4096 to more closely match most filesystems block size.

MVStore: the store is now auto-compacted automatically up to some point, to avoid very large file sizes. This area is still work in progress.

Introduce a queue when doing table locking to prevent session starvation.

don't lock the META table in verifyMetaLocked(), since we're just going to throw an exception if it wasn't locked already

some minor renaming and code movement around table locking to make it easier for me to follow the code