codesniffer cleanups

�� Automatic code style fixes

optionally search one language only

output info on similar chunk fetching

helps with figuring out how fast the store is

refactoring to make models selectable

This makes it much easier to add new models. Models can now be selected
via the configuration

Use overlapping chunks, prepare for new models

removed K-D Tree vector storage

Since this implementation does not have any advantages over the SQLite
storage it makes no sense to keep it. Other storage backends might come
though at a later time

avoid empty chunks

optionally use text renderer for chunking

added a few todos

do not use very small pages as source

These are usually not helpful as context, but may throw off the nearest
neighbor search.

add index clearing, cleanup

fix chunk access by ID in sqlite backend

firs go at abrstracting the storage backend and using sqlite

Requires the dev branch of the sqlite plugin

added info method for kd tree inspection

Faster (and cheaper) reindexing

We can reuse the previous data if the page hasn't changed

More robustness in creating the index

Retry failed API connections, do not abort the whole indexing and rather
skip a chunk. CLI testing tool for the split mechanism

don't index hidden pages

fix logging in CLI mode

Check ACLs before using sources

some more doc blocks

support chatting

initial checkin. working vector storage and similarity search