Apparently the nlohmann library is not available in the standard
repositories.  I would rather build it than add universe deps.

Update JSON build dependencies, change the dockerfile and other
CI files that relate to this.  Also update target mtxclient
revision.

Updated Dutch translation (thanks @Vistaus )

Fix initial sync loop

Attempt to fix issue #19 by increasing the lmdb max_dbs setting.

Update nheko_de.ts (German Translations)

- Update version numbers and documentation
- Fix github releases oauth key

Colors are generated asynchronously now and the TimelineItem is
updated when the color generation finishes.  This allows the UI
to stay responsive while new colors are being generated.

Preparing for 0.6.3 release

escape id when joining a room