This reverts commit 0f55204522.

This breaks using voice files like mb-de5-en. It could also use
named values for the stress rules (e.g. 'first-syllable').

Keyword stressRule in voices.c handles setting langopts->stress_rule.

tr_languages.c still contains the setting for some languages that don't have a language file yet.

Contributes to:
Issue #218, https://github.com/espeak-ng/espeak-ng/issues/218

Contributes to:
Issue #218, https://github.com/espeak-ng/espeak-ng/issues/218

Changes:
language files have a new keyword letterVowel. It can be a latin alphabet from a-z or a hex value (used by bulgarian).
Errors in parsing the values are only reported, nothing is done about them.

About testing:
I haven't noticed any differences in the output audio with letterVowel set or unset in any tested language. The code seems to work and the correct bits seem to be set, but I don't know how to confirm from the final audio.

TODO:
1. Write better documentation in docs/voices.md
2. The code uses new_translator. Should it use translator instead?

Add ar1 mbrola support
Modify ar2 mbrola support

This is because the emoji are language specific.

Supporting phoneme-based voices in espeak-ng is currently complex,
and has issues that need to be fixed in the core code before
adding support for them.

Creating  the language  variant , swiss french. Primarily for counting
as Swiss French uses huitante  for 80 and ,  like the Belgians septante
eand nonante for  70 and 90.

1.  Store the encoding enumeration values in the Translation
    object, instead of the charset table.

2.  Use the encoding.c charset table data instead of the ones
    in translate.c.

3.  Remove the charset language file option -- it is only used
    in the Arabic language file, but is used incorrectly there.

4.  Specify ISO 8859-6 for the 8-bit encoding for Arabic instead
    of UTF-8, so that espeakCHARS_8BIT and espeakCHARS_AUTO work
    correctly for Arabic.