Add Submodule Demo into CQL repo

[baseTwo]

Before starting with this, pick up #428 first

Move demo projects into another repo and include them as submodule in the cql repo. See related #440

See my notes on submodules: https://firely.atlassian.net/wiki/x/EAD5Yg

[baseTwo]

We already have 3 submodules, it's a burden already to juggle. Won't do until a better solution is found