log view: keyboard covers the last lines of text, making selecting/editing hard in that area

[r10s]

at best, the input area should shrink, maybe just a flag (ahh, input-accessory hell again :) if in doubt, a dirty hack would be to add a number of empty lines to the end, for a log, probably good enough.

for details see: https://support.delta.chat/t/two-small-tweaks-to-improve-the-log-screen-in-dc-ios/2991