French issues to fix before training again

[zeehio]

• Fix GPOS questions (19376f8)
• Add GPOS questions for content and non-content categories
• Replace the phoneme '@' with 'ax' ('@' is used in hts labels, may lead to confusion)

  festcat-voice-builder/data/fr/fix_labels.py

  Line 231 in 19376f8

  def fix_labinfo(labinfo):

• Replace the phonemes that include a number for phonemes without numbers (numbers are used to mark syllabification stress in some phoneme formats) P2->pdeux, P9->pneuf... (2 and 9 are the SAMPA phonemes )
• Replace uppercase phonemes by lowercase phonemes, or at least make sure the scripts work in case insensitive filesystems or at least document that limitation)
• Fix https://github.com/MycroftAI/mimic-french/blob/development/src/lang/fr_phoneset.c accordingly
• Fix mimic-french lexicon and LTS rules accordingly