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

Revert "ru: 'х' made less stressed"

This reverts commit 33c9e800a3.

This commit made the [x] phoneme not audible, and made it act like
a glottal stop in words like мягкий.

This reverts commit 223ff9c8ad.

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

The custom n vowel in ph_english did not specify a lengthmod and
the call to the base n did not set that value.

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 _-_

It is possible -- especially at higher speeds -- for the n at the
end of a word to be velarised if the next word starts with a velar
plosive. I prefer the velarised sound between word boundaries, but
others do not. As such, limit the velarisation to within the word
only.

[1]	https://en.wikipedia.org/wiki/English_phonology

There is no fr-CA language dialect dialect file, nor has there
been in the espeak/espeak-ng history.

The fr-CA phoneme table defined the additional phonemes [U], [y"],
[E:], and [A]. The fr-FR phoneme table mapped these to [u], [y],
[E], and [a] respectively. This meant to describe the phonemes that
have not been merged in fr-CA, but have merged in fr-FR, as described
in https://en.wikipedia.org/wiki/Quebec_French_phonology.

The only use of these phonemes in the French dictionary was with
the word "tramway" using [E:]. This has been replaced with [E] to
match the rest of the dictionary file transcriptions, and those
phonemes for fr-CA have been removed.

If fr-CA is supported in the future, the French dictionary would
need to be modified to reverse the merger of the phonemes that are
not merged in fr-CA, with the merge logic being performed in the
fr-FR phoneme table like in the code being removed in this commit.