We currently have two switch statements. Every key should go to only one
of them.

The switch case in LoadVoice() currently mixes voice and language
options. This change will start separating them into two functions.

CheckTranslator will be moved to langopts.c. In the future there should
be no need to use it in voices.c. There will be other temporary
solutions also.

This removes these words from dictionary and uses translation rules
instead. Result is to shorten the i.

See #1337 and #1388.

1. Rewrite cmn_rules. Vowel will be spoken as Mandarin only when it's
with a tone number. Otherwise, it will be regarded as English. This will
make English words translated more correctly.
2. Fix issue of word item in cmn_listx not taking effect.
3. Fix dictionary_skipwords bug. It should be injected when re-structing
method TranslateWord3.

See #1388 and #875.

Add some rules and exceptions for italian language.

Closes #1194.

Windows: add mto dict

Russian: improve numbers and add words

Code cleanup: relocate functions & remove unused #defines

Fix vowels link

Note: Strange that FLAG_ALT7 is used but ALT4-ALT6 are not. Same with
R6p.

utf8_nbytes() is only used in dictionary.c. Others are moved to common.c

fix compilation on windows

fb06936c b52d1f3afd and c4d8976fbc broke it.