net-im/{mtxclient,nheko} update to latest upstream releases
These two go together quite closely. Release notes at
https://github.com/Nheko-Reborn/mtxclient/releases/tag/v0.3.0
https://github.com/Nheko-Reborn/nheko/releases/tag/v0.7.0
Mostly more features for rich-IM purposes.
Fighting with the nheko build shows me we rather need a port for
lmdb++ and tweeny.
Reported by: portscout