Rework rules for Belarusian and update phonemes

This patch strip out dependency on Russian, as its complicated relationship
between spelling and pronunciation overburden rules for Belarusian. The rules
themselves are also added. They don't have devoicing at the end of the words
for now. Also, gemination of consonants doesn't work as expected, as it seems
on the top of this rule some other rules apply. This after-processing is
responsible also for the strange behaviour of ending [a].

phsource/ph_belarusian

@@ -2,48 +2,64 @@
 //  Belarusian
 //====================================================
 
-
 phoneme a
-  import_phoneme ru/a
-endphoneme
-
-phoneme O
-  vwl starttype #o endtype #o
-  ipa ɔ
-  length 100
-  FMT(vwl_ru/8)
+  vwl   starttype #a  endtype #a
+  ipa a
+  length 180
+  FMT(vowel/a)
 endphoneme
 
 phoneme i"
-  import_phoneme pl/y
+  vwl starttype #i endtype #i
+  ipa ɨ
+  length 180
+  FMT(vowel/ii#_2)
 endphoneme
 
 phoneme ts
-  import_phoneme consonants/ts
-  ipa t̻͡s
+  CALL consonants/ts
+  voicingswitch dz
+  ipa t̻͡s̪
 endphoneme
 
 phoneme ts;
-  import_phoneme pl/ts;
+  CALL base1/tS;
+  voicingswitch dz;
   ipa t̻͡s̪ʲ
 endphoneme
 
 phoneme ts.
-  import_phoneme sr/tS
+  vls pla afr sib
   ipa ʈ͡ʂ
+  lengthmod 2
+  voicingswitch dz.
+  Vowelin f1=0  f2=2300 200 400  f3=-100 80
+  WAV(ustop/tsh_sr, 50)
 endphoneme
 
 phoneme dz
-  import_phoneme consonants/dz
+  CALL consonants/dz
+  voicingswitch ts
   ipa d̻͡z̪
 endphoneme
 
 phoneme dz;
-  import_phoneme pl/dz;
+  CALL base1/dZ;
+  voicingswitch ts;
   ipa d̻͡z̪ʲ
 endphoneme
 
 phoneme dz.
-  import_phoneme sr/dZ
+  vcd pla afr sib
   ipa ɖ͡ʐ
+  lengthmod 5
+  voicingswitch ts.
+  Vowelin f1=2  f2=2300 200 400  f3=100 80
+  Vowelout f1=2  f2=2300 250 300  f3=100 80 brk
+
+  IF PreVoicing THEN
+    FMT(dzh/xdzh)
+  ENDIF
+
+  FMT(dzh/dzh) addWav(ufric/sh_pzd2)
 endphoneme

phsource/phonemes

@@ -1819,6 +1819,9 @@ include ph_yue
 
 // *** Tables extending base2 ***
 
+phonemetable be base2
+include ph_belarusian
+
 phonemetable chr base2
 include ph_cherokee
 
@@ -2046,8 +2049,3 @@ include ph_uzbek
 
 phonemetable qdb en
 include ph_langbelta
-
-phonemetable be ru
-include ph_belarusian
-
-phonemetable ms id