Fix #1083 and improve some things in German

See discussion in #933.

if this was not set in spelling rules already

as phoneme set for both is the same, rename phoneme translation file to in

There are small differences between diphone set of the voices, but they are not used from espeak-ng

There are small differences for diphone sets, but these are not used
from eSpeak NG.

E.g. for 'port' this goes through following transformations:

1. written 'port' to phonetic [p'o*@-tS] for eSpeak NG
2. espeak [*] was mapped to MBROLA [r] and [@-] was just skipped
resulting [rt] which is not allowed diphone in br1 voice.

Description of fix:
mapping phonetic [*@-] to [r2] (and skipping [@-]) makes [r2-...] which is
in diphone database. That fixed warnings:

mbrola: Warning: r-t unkown, replaced with _-_
mbrola: Warning: r-d unkown, replaced with _-_
mbrola: Warning: r-n unkown, replaced with _-_
mbrola: Warning: r-m unkown, replaced with _-_
mbrola: Warning: r-s unkown, replaced with _-_

These are some improvements to the german voices, both default and mbrola. It fixes some sounds of phonemes and also pronunciation of words. I also modified the mbrola phoneme and voice files to make them sound more natural. The stressLength setting is that it matches the way espeak deals with the lengths.