Update macOS building dependencies now that libolm is available in Homebrew.  Thanks @aaronraimist 

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Implemented message background highlight feature as per issue #193

Fix nheko build(uses mtxclient device-verification)

Currently translated at 100.0% (277 of 277 strings)

Translation: Nheko/nheko
Translate-URL: http://weblate.nheko.im/projects/nheko/nheko-master/de/

(This is such a hack and will probably break, but it works for now for
most cases...)

This is necessary to support having a picker within QML.
Eventually, this should replace the existing widget-based one.

In the future we should probably add a gradient when clipped...

closes #94

Update Ubuntu Build and Install Instructions