Implement horse-hoarse merger for en-US / general american (#1901)

in general american, for and four are homophones, see
https://en.wiktionary.org/wiki/four#Pronunciation_2
https://en.wiktionary.org/wiki/for#Pronunciation

This is due to the horse-hoarse merger, see

https://en.wikipedia.org/wiki/English-language_vowel_changes_before_historic_/r/#Horse%E2%80%93hoarse_merger

This PR accompanies for this merger on the pronunciation level.

phsource/ph_english_us

@@ -243,12 +243,12 @@ endphoneme
 phoneme o@
   vwl  starttype #o  endtype #@
   length 250
-  ipa oː|ɹ
+  ipa ɔː|ɹ
   IF nextPhW(r) THEN
-    ipa oː
+    ipa ɔː
   ENDIF
   IfNextVowelAppend(r)
-  FMT(vwl_en_us/or)
+  FMT(vwl_en_us/oor)
 endphoneme
 
 

tests/language-phonemes.test

@@ -43,7 +43,7 @@ test_phwav en-GB-scotland 01bee5d39e42f399a67ea16266d633f073e48693 "ma na Na pa
 test_phwav en-GB-x-gbclan dffaba55b53a841d06889a9a6696e3e5280a4dbf "ma na Na pa ta ka ba da ga fa Ta sa Sa xa ha va Da za Za tSa dZa la ra ja wa t2a t#a d#a z#a r-a z/2a w#a m- n- N- _:_ mI mE ma m0 mV mU mi: mA: mO: mu: m3: mA@ mO@ mo@ mU@ mi@3 mIR mVR mi@ me@ mi m@ m3 me# mI# mI2 meI maI mOI moU maU maa mO2 maI@ maI3 maU@"
 test_phwav en-GB-x-gbcwmd bc915f0d2a0ec699dfe169aef3f69aac2a5ba2f7 "ma na Na pa ta ka ba da ga fa Ta sa Sa xa ha va Da za Za tSa dZa la ra ja wa t2a t#a d#a z#a r-a z/2a w#a m- n- N- _:_ mI mE ma m0 mV mU mi: mA: mO: mu: m3: mA@ mO@ mo@ mU@ mi@3 mIR mVR mi@ me@ mi m@ m3 me# mI# mI2 meI maI mOI moU maU maa mO2 maI@ maI3 maU@"
 test_phwav en-GB-x-rp 5b1cfb0721608b235f23eb1b36e88a7e4189388e "ma na Na pa ta ka ba da ga fa Ta sa Sa xa ha va Da za Za tSa dZa la ra ja wa t2a t#a d#a z#a r-a z/2a w#a m- n- N- _:_ mI mE ma m0 mV mU mi: mA: mO: mu: m3: mA@ mO@ mo@ mU@ mi@3 mIR mVR mi@ me@ mi m@ m3 me# mI# mI2 meI maI mOI moU maU maa mO2 maI@ maI3 maU@"
-test_phwav en-US a265818000ea1d39668ae860a4f5a96f4b3992a1 "ma na Na pa ta ka ba da ga fa Ta sa Sa xa ha va Da za Za tSa dZa la ra ja wa t2a t#a d#a z#a r-a z/2a w#a m- n- N- _:_ mI mE ma m0 mV mU mi: mA: mO: mu: m3: mA@ mO@ mo@ mU@ mi@3 mIR mVR mi@ me@ mi m@ m3 me# mI# mI2 meI maI mOI moU maU maa mO2 maI@ maI3 maU@"
+test_phwav en-US bfa628c50f1cad5cc0ff0adad905f8c2d855b4ac "ma na Na pa ta ka ba da ga fa Ta sa Sa xa ha va Da za Za tSa dZa la ra ja wa t2a t#a d#a z#a r-a z/2a w#a m- n- N- _:_ mI mE ma m0 mV mU mi: mA: mO: mu: m3: mA@ mO@ mo@ mU@ mi@3 mIR mVR mi@ me@ mi m@ m3 me# mI# mI2 meI maI mOI moU maU maa mO2 maI@ maI3 maU@"
 test_phwav en-US-nyc 09858d35ec3a09647beee153cbac7de881c9062d "ma na Na pa ta ka ba da ga fa Ta sa Sa xa ha va Da za Za tSa dZa la ra ja wa t2a t#a d#a z#a r-a z/2a w#a m- n- N- _:_ mI mE ma m0 mV mU mi: mA: mO: mu: m3: mA@ mO@ mo@ mU@ mi@3 mIR mVR mi@ me@ mi m@ m3 me# mI# mI2 meI maI mOI moU maU maa mO2 maI@ maI3 maU@"
 test_phwav eo cc2f7f352c6d299c81f6f95e730883f052dbc597 "ma na pa ta ka ba da ga fa sa Sa xa ha va za Za tsa tSa dza dZa la ja wa ra _:_ ma me mo mi mu maU meU maI meI moU muI"
 test_phwav es 4758bff06486f6a37666f050ada0f04f0b762fad "ma na n^a pa ta ka ba da ga fa Ta sa Sa J^a xa Da tSa la l^a *a Ra ra v#a _:_ ma ma/ me me/ mE mi mo mo/ mu moI"

tests/ssml/spec-example-1.expected

@@ -1,10 +1,10 @@
 
 
 
-juː hæv fˈoː͡ɹ nˈuː mˈɛsɪd͡ʒᵻz
+juː hæv fˈɔː͡ɹ nˈuː mˈɛsɪd͡ʒᵻz
 
 ðə fˈɜːst ɪz fɹʌm stˈɛfəni wˈɪljəmz ænd ɚɹˈa͡ɪvd æt
-θɹˈiː fˈoː͡ɹɾi fˈa͡ɪv pˌiːˈɛm
+θɹˈiː fˈɔː͡ɹɾi fˈa͡ɪv pˌiːˈɛm
 
 ðə sˈʌbd͡ʒɛkt ɪz skˈiː tɹˈɪp