Updated db2 and related modules to latest version.

Make ssb-browser-core be much closer to standard ssb stack. No more SSB.net.something for secret stack plugins. This was mostly a relic from before there was ssb-db2, just hadn't had a chance to clean it up. This removes partial replication as well, will be superseed by partial replication using meta feeds once ready.

• Major improvements to the README to make it easier to get started using ssb-browser-core
• Simplify singleton
• Remove DHT, can be enabled using extraModules + config if needed
• Remove ssb-blob-files, can be enabled using extraModules if needed

Update ssb-db2 and use better methods for initial sync. Update ssb-ebt to fix race condition

This changes quite a lot about how connections are handled. SSB-EBT is now used instead of our soft-fork, friends is upgraded to 5 and a replication scheduler is now used

Breaking change because of the where syntax.

Use standard modules instead of specific index

Bumping related libraries for minor fixes

This is a major change where the existing db has been converted into its own module ssb-db2. Furthermore this includes a lot of changes to jitdb that makes it a lot more pleasant to use.