Fix bool

See merge request memri/pod!33

Sql injection prevention

See merge request memri/pod!35

Remove unused libraries, enable LTO in releases

See merge request memri/pod!34

It makes sense now since docker builds
are now somewhat cached/incremental.

Create "pod.db" under /db, mount /db to container

See merge request memri/pod!32

reduce docker layer size

See merge request memri/pod!31

docker cache dependencies

See merge request memri/pod!30

Make Pod compatible with old sqlcipher versions

See merge request memri/pod!29

In particular, make it compatible with version 3.4, as used in ubuntu-20.04.